Additive transfer film suitable for cook-in end use

ABSTRACT

A multilayer film has a first layer and a second layer. The first layer comprises an additive, a binder, and a crosslinking agent. The additive is a flavor, fragrance, colorant, antimicrobial agent, antioxidant, chelating agent, and/or odor absorbent. The binder is a polysaccharide and/or a protein. The crosslinking agent comprises a compound with at least two carbonyl groups. The second layer comprises a non-water-soluble thermoplastic polymer comprising at least one member selected from the group consisting of polyolefin, polyamide, polyester, polyvinylidene chloride, polyvinyl chloride, and polystyrene. Each of the additive, binder, and crosslinking agent are present throughout a thickness of the first layer. Preferably, the first layer is coated onto the second layer, which is preferably a non-water-soluble thermoplastic polymer, e.g., polyolefin, polyamide, and/or polyester. The film is especially useful for cook-in applications, in which a food product (preferably comprising uncooked meat) is packaged in the film with the coated layer against the meat. The meat is then cooked and the additive transfers to the meat, and purge can be very low. The invention also pertains to a process for preparing a cooked food product, process for making a coated film, and articles formed from the film, such as bags and casings.

This application is a continuation of application Ser. No. 09/009,524,filed Jan. 20, 1998, now U.S. Pat. No. 6,667,082.

FIELD OF THE INVENTION

The present invention relates generally to multilayer films, and methodsof using same, especially to produce a packaged food product comprisingcooked meat having a flavorant and/or fragrance and/or odor absorbentand/or colorant and/or antimicrobial, and/or antioxidant, and/orchelating agent therewith.

BACKGROUND OF THE INVENTION

The food packaging industry uses packaging films from which bags andcasings are made which are such that they may be used in cook-inapplications, i.e., uses in which a food product is packaged in thefilm, following which the food product is cooked while packaged in thefilm. The term “cook-in,” as used herein with respect to packagingmaterials such as films, refers to packaging material structurallycapable of withstanding exposure to cook-in time-temperature conditionswhile surrounding a food product. Cook-in foods are foods cooked in thepackage. The cooked product can be distributed to the customer in theoriginal bag or the bag removed and the meat portioned for repackaging.Cook-in time-temperature conditions typically refer to a long slow cook,for example submersion in hot water at 131° F. to 149° F. for 12 hours.However, cook-in can include submersion at from 135° F. to 212° F. for2–12 hours, or from 158° F. to 212° F. for from 1–4 hours.

During cook-in, the package should maintain seal integrity, i.e., anyheat-sealed seams should resist being pulled apart during cook-in.Preferably, the film is heat sealable to itself Additionally, thepackaging film substantially conforms to the packaged food product.Preferably, this substantial conformability is achieved by the filmbeing heat shrinkable under these conditions so as to form a tightlyfitting package. In other words, in an advantageous embodiment, the filmis heat-shrinkable under time-temperature conditions of cook-in, i.e.,the film possesses sufficient shrink energy such that submerging thepackaged food product in hot water will shrink the packaging film snuglyaround the packaged product, representatively up to about 55% monoaxialor biaxial shrinkage at 185° F. Also, during cook-in the film shouldhave food product adherence to restrict “cook-out,” i.e., the collectionof juices between the surface of the contained food product and themeat-contact surface of the packaging material; cook-out is commonlyreferred to as “purge.” In this manner, product yield is increased bythe food product retaining moisture, and the aesthetic appearance of thepackaged product is not diminished by the presence of the purge.

For ham, beef, turkey, and other meat products, it is often desirable toexpose the surface of the meat product to an additive, to simply coat oreven suffuse the additive into the surface of the meat product. Theadditive can be, for example, a colorant or flavorant. The use of asmoke-containing additive is particularly common, the smoke providingboth a flavor effect and a color effect to the meat product.

If the surface of the product is to be exposed to an additive, forexample to produce a smoked meat product, it has for some time beenstandard practice in the industry to first package the meat product in afilm, followed by cooking the meat product while it is packaged,followed by removing the cooked meat from the package and placing themeat in a smokehouse to impart smoke coloration and flavor. The smokedmeat product is thereafter repackaged in another film, and shipped to awholesaler, retailer, or consumer.

In addition, the unpackaging, smoking, and repackaging of the cookedmeat product exposes the cooked meat product to microbial contamination,resulting in shorter shelf life for the cooked meat product. However,the need to unpackage, smoke, and repackage the meat product is a laborintensive, expensive process for the manufacturer of the smoked cookedmeat product. Furthermore, the smoking step is inefficient in that onlyabout 70% of the smoke is effective as a flavorant/colorant, with theremaining 30% of the smoke accumulating on non-food surfaces in thesmokehouse, necessitating cleaning, etc. and generating waste.

Thus, it would be desirable to provide a packaged product without havingto package, cook, unpackage, smoke, and repackage, together withavoiding the handling required for each of these operations. It would bedesirable to entirely avoid the need to unpackage and repackage andthereby avoid the potential for microbiological contamination, togetherwith avoiding the waste from discarding the original package, theinefficiency and waster from the smoking in a smokehouse, as well as toavoid the lower shelf life of the finally-packaged product, resultingfrom microbiological contamination due to excess handling of the cookedmeat product.

SUMMARY OF THE INVENTION

The present invention solves the longstanding problem described above,by providing a film which can be coated with an additive which istransferred to a product during cook-in, while avoiding the handling,waste, inefficiency, and contamination generated by the steps ofunpackaging, smoking, and repackaging in accordance with the prior art.Moreover, during cooking of a food product surrounded by the film, thebinder and additive are both transferred from the film to the foodproduct. After cooking, the film can be stripped off of the food productcleanly (less the binder and additive, which are transferred to thefood), i.e., without any food (meat) pull-off, even though the coatingprevents or reduces purge. Thus, the film according to the invention iscapable of being used during cook-in to prevent or reduce purge, providea uniform transfer of additive(s) to the surface of the meat product,while at the same time allowing a clean separation of the cooked food(especially meat) from the film, without tear-off

In addition, the film of the present invention can be easilymanufactured, i.e., the additive-containing coating can be applied tothe film using coating or printing technology, such as gravure coatingor printing, lithographic coating or printing, etc. The coating can beprinted onto the film in the pattern of the product or a portion of theproduct, while avoiding printing the coating onto areas to be sealed.The film of the present invention is also more efficient than, forexample, application of smoke to meat in a smokehouse, becausesubstantially all of the liquid smoke coating is transferred to themeat, without waste. The film is also dry, so that it can be preparedwith the additive(s) present, and stored before use, unlike films whichhave a wet coating thereon.

The present invention resulted from the discovery that films can beuniformly coated with certain binders in a form which are not quick tobecome hydrated or dissolved at the conditions of use. That is, theinvention resulted from the discovery of binders which, together withcrosslinkers, control the initial adhesion of the additive to the film,reduce the rate of hydration of the coating and the release of theadditive, and further the binding of the coating to, for example, acooked meat product during the cooking step. The result is that theadditive-containing coating is present on the film in a form whichprevents or reduces smearing of the coating when, for example, a coatedfilm casing is filled with the meat product or flowing of the additiveduring cooking of the product, i.e. resulting in a mottled distributionof the additive. It was also discovered that the binder holds anadditive which is released during cook-in, so that the meat product isflavored/colored in a desired manner and degree, without having tounpackage, treat, and repackage the product. In this manner, the shelflife of the resulting packaged product is increased relative to packagedproducts produced in accordance with the prior art method which requiresunpackaging and repackaging. In addition, certain binders werediscovered to be better than others, as were particular combinations ofbinders, such as the combination of hydroxypropyl starch with acrosslinking agent (e.g., liquid smoke), together, optionally, withfibrinogen as a second binder. In addition, particular cookingprocedures were discovered which result in reduced purge when using afilm in accordance with the present invention. Moreover, the pH of thecoating composition was discovered to have an effect on the quantity ofpurge loss as well as the quality of the transfer of an additive fromthe film to meat packaged in the film. For example, a pH of from about 2to 6 is considered to be a preferred range for the pH of the coatingformulation used to coat a substrate thermoplastic film.

As a first aspect, the present invention pertains to a multilayer filmcomprising a first layer and a second layer. The first layer comprises:(i) an additive comprising at least one member selected from the groupconsisting of flavor, fragrance, colorant, antimicrobial agent,antioxidant, chelating agent, and odor absorbent, (ii) a bindercomprising at least one member selected from the group consisting ofpolysaccharide and protein, and (iii) a crosslinking agent comprising acompound with at least two carbonyl groups. The second layer comprises anon-water-soluble thermoplastic polymer comprising at least one memberselected from the group consisting of polyolefin, polyamide, polyester,polyvinylidene chloride, polyvinyl chloride, and polystyrene. Each ofthe additive, binder, and crosslinking agent are present throughout athickness of the first layer. The presence of a crosslinking agentresults in a crosslinked polymer network.

Preferably, the additive comprises at least one member selected from thegroup consisting of caramel, liquid smoke, FD&C Blue No 1, FD&C Blue No2, FD&C Green No 3, FD&C Green No 6, FD&C Orange B, FD&C Red No 3, FD&CRed No 40, FD&C Yellow No 5, FD&C Yellow No 6, a lake of one or moreFD&C colorant, natural brown, annatto extract, beet powder,canthaxanthin, β-Apo-8′-carotenal, carotene, cochineal extract, carmine,grape color extract, synthetic iron oxide, paprika, riboflavin, andtitanium oxide, malt, natural colorant, spice, bacteriocin,allyisothiocyanate, monolaurin,1-[2-(2,4-dichlorophenyl)-2-(propenyloxy)ethyl]-1H-imidazole, silver,benzoic acid, benzoate, hydroxycinnamic acid derivative, essential oil,sorbic acid, salt of sorbic acid, benzoate, methyl p-hydroxybenzoate,propyl p-hydroxybenzoate, p-hydroxybenzoic acid, sodium benzoate,propionic acid, salt of propionic acid, sodium lactate, dimethyldicarbonate, diethyl dicarbonate, sulfite, diethyl pyrocarbonate, EDTA,butylated hydroxyanisole, butylated hydroxytoluene, propyl gallate,dilauryl thiodipropionate, thiodipropionic acid, gum guaiac, tocopherol,acetate, citrate, gluconate, oxystearin, ortho-phosphate,meta-phosphate, pyro-phosphate, polyphosphate, phytate, sorbitol,tartrate, thiosulfate, and lysozyme,

Preferably, the additive comprises a colorant and the multilayer film,when subjected to a Standard Mottling Test, exhibits a Gray Scalestandard deviation of less than about 20; more preferably, from about 0to 20; still more preferably, from about 0 to 19; yet still morepreferably, from about 0 to 18; even yet still more preferably, fromabout 12 to 18; even yet still more preferably, from about 0 to 17; evenyet still more preferably, from about 0 to 16; even yet still morepreferably, from about 0 to 15; even yet still more preferably, fromabout 0 to 14; even yet still more preferably, from about 0 to 13; evenyet still more preferably, from about 0 to 12.

Preferably, the binder comprises at least one member selected from thegroup consisting of alginate, methyl cellulose, hydroxypropyl starch,hydroxypropylmethyl starch, hydroxymethyl cellulose, hydroxypropylcellulose, hydroxypropylmethyl cellulose, carboxymethyl cellulose,cellulose esterified with 1-octenyl succinic anhydride, chitin, andchitosan, gliadin, glutenin, globulin, albumin (especially in the formof gluten), prolamin (especially corn zein), thrombin, pectin,canageenan, konjac flour-glucomannin, fibrinogen, casein (especiallycasein milk protein), soy protein (especially soy protein isolates),whey protein (especially whey milk protein), and wheat protein.

Another preferred grouping of binders comprises at least one memberselected from the group consisting of: (A) polysaccharide esterifiedwith at least one member selected from the group consisting of: aceticanhydride, propionic anhydride, alkyl-propionic anhydride, butyricanhydride, alkyl-butyric anhydride, succinic anhydride, alkyl-succinicanhydride, maleic anhydride, alkyl-maleic anhydride, adipic anhydride,alkyl-adipic anhydride, and vinyl acetate; and (B) polysaccharideetherified with at least one member selected from the group consistingof acrolein, epichlorihydrin, ethylene glycol, ethylene glycol oligomer,propylene glycol, propylene glycol oligomer, ethylene oxide, andpropylene oxide.

Yet another preferred first layer comprises at least two differentbinders, i.e.: (A) a first binder comprising at least one memberselected from the group consisting of alginate, methyl cellulose,hydroxypropyl starch, hydroxypropylmethyl starch, hydroxymethylcellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose,carboxymethyl cellulose, cellulose esterified with 1-octenyl succinicanhydride, chitin, and chitosan; and (B) a second binder comprising atleast one member selected from the group consisting of gliadin,glutenin, globulin, albumin (especially in the form of gluten), prolamin(especially corn zein), thrombin, pectin, canageenan, konjacflour-glucomannin, fibrinogen, casein (especially casein milk protein),soy protein, whey protein (especially whey milk protein), and wheatprotein. More preferably, the binder comprises hydroxypropyl starch.

Another preferred group of binders comprises at least one memberselected from the group consisting of: (A) at least one member selectedfrom the group consisting of polysaccharide esterified with an anhydrideof the formula: [CH₃(CH₂)_(n)—CO]₂—O where n=from 0 to 6, as well asalkyl-substituted anhydrides thereof, (B) CH₃(CH₂)_(n)—COCl, wheren=from 0 to 6; (C) alkyl-substituted acid chlorides ofCH₃(CH₂)_(n)—COCl, where n=from 0 to 6; (D) modified polysaccharidewhich results from the etherification of a base polysaccharide with atleast one member selected from the group consisting of acrolein,epichlorohydrin, ethylene glycol, ethylene glycol oligomer, propyleneglycol, propylene glycol oligomer, ethylene oxide, and propylene oxide.

Preferably, the second layer comprises at least one member selected fromthe group consisting of polyamide 6, polyamide 66, polyamide 9,polyamide 10, polyamide 11, polyamide 12, polyamide 69, polyamide 610,polyamide 612, polyamide 61, polyamide 6T, polyamide MXD6, copolyamide,polyethylene homopolymer, ethylene/alpha-olefin copolymer,anhydride-modified ethylene/alpha-olefin copolymer, ethylene/vinylacetate copolymer, ethylene/acrylic acid copolymer, ionomer (especiallyionomers of ethylene/methacrylic acid and ethylene/acrylic acid),ethylene/methacrylic acid copolymer, anhydride-modifiedethylene/methacrylic acid copolymer, polypropylene homopolymer,propylene/C₄₋₁₀ alpha-olefin copolymer, polyethylene terephthalate,PETG, and polyalkylhydroxy acid.

Preferably, the multilayer film has a total free shrink (i.e., L+T) offrom about 0 to 10 percent at a temperature of 185° F.; more preferably,from about 10 to 150%; still more preferably, from about 10 to 100%.

Preferably, the additive is bound to the binder with at least one memberselected from the group consisting of a covalent bond, an ionic bond, ahydrogen bond, and a dipole-dipole interaction.

Preferably, the crosslinking agent comprises at least one memberselected from the group consisting of malose, glutaraldehyde, glyoxal,dicarboxylic acid, ester of dicarboxylic acid, urea formaldehyde,melamine formaldehyde, trimethylol-melamine, organic compound containingat least 2 sulfhydryl groups, and a component in liquid smoke comprisingat least two carbonyl groups.

Preferably, the second layer is directly adhered to the first layer.

Preferably, the film further comprises a third layer which is betweenthe first layer and the second layer. This third layer can serve as aprimer which is applied to the second layer, for the subsequentapplication of the first layer. Additionally or alternatively, the thirdlayer can contain an additive, such as one or more of the additiveswhich can be present in the first layer, and/or a release agent, and/ora crosslinking agent. Preferably, the third layer comprises at least onemember selected from the group consisting of polysaccharide and protein;more preferably, at least one member selected from the group consistingof: alginate, methyl cellulose, hydroxypropyl starch,hydroxypropylmethyl starch, hydroxymethyl cellulose, hydroxypropylcellulose, hydroxypropylmethyl cellulose, carboxymethyl cellulose,cellulose esterified with 1-octenyl succinic anhydride, chitin, andchitosan, gliadin, glutenin, globulin, albumin (especially in the formof gluten), prolamin (especially corn zein), thrombin, pectin,canageenan, konjac flour-glucomannin, fibrinogen, casein (especiallycasein milk protein), soy protein, whey protein (especially whey milkprotein), and wheat protein.

Preferably, the multilayer film further comprises a third layer, withthe first layer being between the second layer and the third layer.Preferably, the third layer comprises at least one member selected fromthe group consisting of polysaccharide and protein. More preferably, atleast one member selected from the group consisting of alginate, methylcellulose, hydroxypropyl starch, hydroxypropylmethyl starch,hydroxymethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethylcellulose, carboxymethyl cellulose, cellulose esterified with 1-octenylsuccinic anhydride, chitin, and chitosan, gliadin, glutenin, globulin,albumin (especially in the form of gluten), prolamin (especially cornzein), thrombin, pectin, canageenan, konjac flour-glucomannin,fibrinogen, casein (especially casein milk protein), soy protein, wheyprotein (especially whey milk protein), and wheat protein. This thirdlayer, which serves as an “overcoat” over the first layer, can furthercomprise an additive, such as one or more of the additives present inthe first layer, and/or a meat adhesion enhancing additive and/or acrosslinking agent. Preferably, the multilayer film further comprises afourth layer which is between the first layer and the second layer.Preferably, the fourth layer serves as a primer layer, as describedabove.

Preferably, the multilayer film, when subjected to a Standard MottlingTest, exhibits a mottling level of from about 1 to about 2.5.

Preferably, the first layer further comprises a plasticizer. Preferably,the plasticizer comprises at least one member selected from the groupconsisting of polyol, sodium citrate, and triethyl citrate.

Preferably, the multilayer film further comprises a third layercomprising at least one member selected from the group consisting ofpolyolefin, polyamide, and polyester. More preferably, the third layercomprises at least one member selected from the group consisting ofethylene/vinyl alcohol copolymer, vinylidene chloride copolymer,polyamide, polyvinyl alcohol, polyhydroxyaminoether, and polyalkylenecarbonate, ethylene/acrylic acid copolymer, polyethylene terephthalate,and ionomer. Preferably, the third layer is an inner layer, and themultilayer film further comprises a fourth layer comprising at least onemember selected from the group consisting of polyolefin, polyamide, andpolyester; more preferably ethylene/vinyl alcohol copolymer, vinylidenechloride copolymer, polyamide, polyvinyl alcohol, polyhydroxyaminoether,and polyalkylene carbonate, ethylene/acrylic acid copolymer, polyester,and polyethylene terephthal ate.

Preferably, the second film layer serves as a seal layer and comprisesat least one member selected from the group consisting of polyolefin,polyamide, and polyester, and preferably, the film further comprises:(i) a third layer which serves as an O₂-barrier layer comprising atleast one member selected from the group consisting of at least onemember selected from the group consisting of ethylene/vinyl alcoholcopolymer, polyvinylidene chloride, polyamide, polyalkylene carbonate,polyvinyl alcohol, and polyester; (ii) a fourth film layer which servesas a first tie layer and which is on a first side of the O₂-barrierlayer and which comprises at least one member selected from the groupconsisting of modified ethylene/alpha-olefin copolymer, modifiedethylene/unsaturated ester copolymer, modified ethylene/unsaturated acidcopolymer, polystyrene and polyurethane; and (iii) a fifth film layerwhich serves as a second tie layer and which is on a second side of theO₂-barrier layer and which comprises comprising at least one memberselected from the group consisting of modified ethylene/alpha-olefincopolymer, modified ethylene/unsaturated ester copolymer, modifiedethylene/unsaturated acid copolymer, polystyrene and polyurethane; and(iv) a sixth film layer which serves as an abuse layer and whichcomprises at least one member selected from the group consisting ofpolyolefin, polyamide, polyester, and polyurethane. More preferably, thefilm further comprises: (i) a seventh film layer which serves as astrength layer and which is between the second layer and the fourthlayer, and which comprises at least one member selected from the groupconsisting of polyolefin, polyamide, polyester, and polyurethane; (ii) aeighth film layer which serves as a strength and balance layer and whichis between the fifth layer and the sixth layer, and which comprises atleast one member selected from the group consisting of polyolefin,polyamide, polyester, and polyurethane; and (iii) a ninth film layerwhich serves as a strength and moisture barrier layer and which betweenthe fifth layer and the sixth layer, and which comprises polyamide.

As a second aspect, the present invention pertains to a process forpreparing a cooked food product, comprising: (A) packaging a foodproduct in a multilayer film in accordance with the first aspect of thepresent invention, and (B) cooking the food product while the foodproduct is packaged in the multilayer film. Preferably, the food productcomprises at least one member selected from the group consisting ofbeef, pork, chicken, turkey, fish, and meat-substitute. Preferably, thefood is cooked at a temperature of from about 145° F. to 205° F. for aduration of from about 1 to 12 hours.

As a third aspect, the present invention is directed to a process forpreparing a cooked food product, comprising: (A) packaging a foodproduct in a multilayer film in accordance with the first aspect of thepresent invention, and (B) cooking the food product at a temperature offrom about 170° F. to 260° F. for a duration of from about 1 to 20minutes, followed by cooking the food product at a temperature of fromabout 145° F. to 205° F. for a duration of from about 1 to 12 hours.

As a fourth aspect, the present invention is directed to a process formaking a coated multilayer film, comprising: (A) coating an outersurface of a substrate film with a film-forming coating compositioncomprising: (i) water; (ii) an additive comprising at least one memberselected from the group consisting of flavor, fragrance, colorant,antimicrobial agent, antioxidant, chelating agent, and odor absorbent,(iii) a binder comprising at least one member selected from the groupconsisting of polysaccharide and protein, and (iv) a crosslinking agentcomprising a compound having at least two carbonyl groups; and (B)drying the coating composition whereby the composition becomes a firstfilm layer, the substrate film comprising at least a second film layer.The substrate film comprises at least one member selected from the groupconsisting of polyolefin, polyamide, polyester, polyvinylidene chloride,polyvinyl chloride, and polystyrene. Preferably, the coating compositionis applied to the film using at least one member selected from the groupconsisting of roll (preferably comma roll, obtained from Hirano Tecseed,of Charlotte, N.C.), gravure, flexographic, meyer rod, reverse angledoctor blade, knife over roll, two roll reverse, three roll reverse,comma roll, and lip coating.

As a fifth aspect, the present invention is directed to an articlecomprising a multilayer film in accordance with the first aspect of thepresent invention, wherein the second layer is sealed to itself oranother film. Preferably, the first layer extends over (i.e., covers)only a portion of the second layer. Preferably, the article comprises atleast one member selected from the group consisting of a bag, abackseamed casing, a pouch, and a thermoformed article. More preferably,the article comprises at least one member selected from the groupconsisting of fin-sealed backseamed casing, lap-sealed backseamedcasing, butt-sealed backseamed casing, side-seal bag, end-seal bag,pouch, and perimeter sealed thermoformed article.

As a sixth aspect, the present invention is directed to a packagedproduct comprising: (A) a film comprising a non-water-solublethermoplastic polymer comprising

at least one member selected from the group consisting of polyolefin,polyamide, polyester, polyvinylidene chloride, polyvinyl chloride, andpolystyrene; (B) a cooked meat product comprising at least one memberselected from the group consisting of beef, pork, chicken, turkey, fish,and meat-substitute; and (C) a layer between the film and the cookedmeat product. The C layer comprises: (i) an additive comprising at leastone member selected from the group consisting of flavor, fragrance,colorant, antimicrobial agent, antioxidant, chelating agent, and odorabsorbent, (ii) a binder comprising at least one member selected fromthe group consisting of polysaccharide and protein, and (iii) acrosslinking agent comprising a compound with at least two carbonylgroups. In the C layer, each of the additive, binder, and crosslinkingagent are present throughout a thickness of the first layer. Preferably,the layer between the film and the cooked meat product is preferentiallyadhered to the meat product, i.e., is adhered to the meat product to adegree so that upon removing the film from the meat product, the C layerremains adhered to the meat product, rather than to the film.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic view of a preferred process for making amultilayer film in accordance with the present invention.

FIG. 2 illustrates a lay-flat view of a bag in accordance with thepresent invention.

FIG. 3 illustrates a packaged product in accordance with the presentinvention.

FIG. 4 illustrates a perspective view of a packaged product inaccordance with the present invention.

FIG. 5A illustrates a first embodiment of a cross-sectional view throughline 5—5 of the packaged product illustrated in FIG. 4.

FIG. 5B illustrates a second embodiment of a cross-sectional viewthrough line 5—5 of the packaged product illustrated in FIG. 4.

FIG. 5C illustrates a third embodiment of a cross-sectional view through5—5 of the packaged product illustrated in FIG. 4.

FIG. 6 illustrates a perspective view of an alternative packaged productaccording to the present invention.

FIG. 7 is a schematic of the setup for carrying out the StandardMottling Test disclosed herein.

FIGS. 8, 9, and 10 are photographs of three different chubs,illustrating 3 different degrees of mottling.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the prefix “alkyl” refers to, and is inclusive of, bothsaturated and unsaturated side chains. In other words, in order tosimplify the text herein, the prefix “alkyl” is inclusive of both“traditional alkyl” sidechains as well as “traditional alkenyl” and“traditional alkynyl” sidechains.

As used herein, the term “binder” refers to a substance which adheres toan additive and/or a surface comprising a thermoplastic polymer and/or aprotein-containing product, such as meat. For example, a preferredpolysaccharide binder for use in the present invention is hydroxypropylstarch, e.g., ¹⁹⁸ hydroxypropyl starch. This binder is capable ofholding, entrapping, or binding to additives such as colorants, flavors,etc., while at the same time being capable of adhering to a surfacecomprising a thermoplastic polymer.

As used herein, the term “flavorant” refers to, and is inclusive of,spice (including, of course, pepper). Liquid smoke is an especiallypreferred flavorant.

As used herein, the term “colorant” is inclusive of the various FD&Ccolorants, together with various other colorants. Preferably, thecolorant comprises at least one member selected from the groupconsisting of FD&C Blue No 1, FD&C Blue No 2, FD&C Green No 3, FD&CGreen No 6, FD&C Orange B, FD&C Red No 3, FD&C Red No 40, FD&C Yellow No5, FD&C Yellow No 6. FD&C Blue No. 1 is the disodium salt of4-((4-(N-ethyl-p-sulfobenzylamino)-phenyl-(2-sulfoniumphenyl)-methylene)-(1-(-N-ethyl-N-p-sulfobenzyl)-sup2,5-cyclohexadienimine).FD&C Blue No. 2 is the disodium salt of 5,5′-indigotin disulfonic acid.FD&C Green No. 3 is the disodium salt of4-((4-(N-ethyl-p-sulfobenzylamino)-phenyl-(4-hydroxy-2-sulfoniumphenyl)-methylene)-(1-(—N-ethyl-N—P-sulfobenzyl)-sup2,5-cyclohexadienimine).FD&C Green No. 6 is 1,4-di-toluidinoanthraquinone. FD&C Red No.3 is thedisodium salt of9-o-carboxyphenyl-6-hydroxy-2,4,5,6,7-tetraiodo-3-isoxanthone(erythrosin). FD&C Yellow No. 5 is the trisodium salt of3-carboxy-5-hydroxy-1-p-sulfophenyl-4-sulfophenylazopyrazole. FD&CYellow No. 6 is the disodium salt of1-p-sulfophenylazo-2-naphthol-6-solfonic acid.

As used herein, the term “film” is used in a generic sense to includeplastic web, regardless of whether it is film or sheet. Preferably,films of and used in the present invention have a thickness of 0.25 mmor less. As used herein, the term “package” refers to packagingmaterials configured around a product being packaged. The phrase“packaged product,” as used herein, refers to the combination of aproduct which is surrounded by a packaging material.

As used herein, the phrase “multilayer film” refers to the combinationof a film comprising a first layer which is an outer layer and whichcontains the binder and the additive, in combination with a second layerwhich comprises a thermoplastic polymer. Although the first layer ispreferably directly adhered to the second layer, the film can optionallycontain one or more additional film layers, such as an oxygen-barrierlayer with or without tie layers in association therewith, additionalbulk and/or strength layers, etc. The first layer is preferably appliedas a coating on a substrate film which comprises the second film layer,alone or in combination with additional film layers as describedimmediately above. The first layer is always an outer film layer. Inarticles according to the present invention, such as bags and casings,the first layer is the inside layer of the film.

As used herein, the phrase “the layer . . . comprising” refers to a filmlayer which has the recited components throughout the entirecross-section of the layer, as opposed to having one or more of therecited components merely on a surface of the layer. Preferably, thedistribution of the recited components is uniform throughout the layer.

As used herein, the phrase “outer layer” refers to any film layer havingless than two of its principal surfaces directly adhered to anotherlayer of the film. The phrase is inclusive of monolayer and multilayerfilms. All multilayer films have two, and only two, outer layers, eachof which has a principal surface adhered to only one other layer of themultilayer film. In monolayer films, there is only one layer, which, ofcourse, is an outer layer in that neither of its two principal surfacesare adhered to another layer of the film.

As used herein, the phrase “drying,” as used with reference to theprocess according to the present invention, refers to the drying of thecoating which forms an outer layer of the film of the invention.Preferably, drying prevents the outer layer of the film from exhibitingsubstantial blocking, i.e., sticking to a degree that blocking ordelamination occurs, with respect to adjacent surfaces of, for example,a film (including both the same or another film), and/or other articles(e.g., metal surfaces, etc.). Preferably, the outer layer has a moisturecontent of less than about 25 percent, based on the weight of the outerlayer; more preferably, from about 0 to 25 percent; still morepreferably, from about 0 to 10 percent; yet still more preferably, fromabout 0 to 5 percent.

As used herein, the term “seal” refers to any seal of a first region ofa film surface to a second region of a film surface, wherein the seal isformed by heating the regions to at least their respective sealinitiation temperatures. The sealing can be performed by any one or moreof a wide variety of manners, such as using a heated bar, hot air,infrared radiation, ultrasonic sealing, etc., and even the use of clipson, for example, a shirred casing, etc. However, a multilayer filmhaving a plurality coextruded layers or layer(s) extrusion coatedthereon are not considered to be heat-sealed to one another by virtue ofthe coextrusion process or the extrusion coating process.

As used herein, the phrase “cook-in” refers to the process of cooking aproduct packaged in a material capable of withstanding exposure to longand slow cooking conditions while containing the food product, forexample submersion in water at 57° C. to 100° C. for 2–12 hours,preferably 57° C. to 85° C. for 2–12 hours; also by submersion in water,or submersion in pressurized steam (i.e., retort) at 57° C. to 121° C.for 2–12 hours, using a film suitable for retort end-use. Cook-inpackaged foods are essentially pre-packaged, pre-cooked foods which maybe directly transferred to the consumer in this form. These types offoods may be consumed with or without warming. Cook-in packagingmaterials maintain seal integrity, and in the case of multilayer filmsare delamination resistant. In certain end-uses, such as cook-incasings, preferably the film is heat-shrinkable under cook-in conditionsso as to form a tightly fitting package. Cook-in films preferably have atendency for adhesion to the food product, thereby preventing“cook-out,” i.e., purge, which is the collection of juices between theouter surface of the food product and the meat-contact surface of thefilm, i.e., the surface in direct contact with the meat. Additionaloptional characteristics of films for use in cook-in applicationsinclude delamination-resistance, low O₂-permeability, heat-shrinkabilityrepresenting about 20–50% biaxial shrinkage at about 185° F., andoptical clarity. For hermetically sealed bags, it is preferred that theexternal surface of the package is subjected to a temperature of atleast about 65° C.; preferably from about 65° C. to 100° C.; morepreferably, from about 71° C. to 100° C.; still more preferably, fromabout 74° C. to 93° C.; and, even yet still more preferably, from about77° C. to 82° C.

As used herein, the phrases “food-contact layer” and “meat-contactlayer” refer to a layer of a multilayer film which is in direct contactwith the food/meat in the package comprising the film. In a multilayerfilm, a food-contact layer is always an outer film layer, as thefood-contact layer is in direct contact with the food product within thepackage. The food-contact layer is an inside layer in the sense thatwith respect to the packaged food product, the food-contact layer is theinside layer (i.e., innermost layer) of the package, this inside layerbeing in direct contact with the food. As used herein, the phrases,“food-contact surface” and “meat-contact surface” refer to an outersurface of a food contact layer, this outer surface being in directcontact with the food within the package.

As used herein, the phrases “meat-adhesion,” “film-to-meat adhesion,”“film-to-food adhesion,” and “adhered”, refer to maintaining directcontact between the meat surface and the meat-contact surface of thefilm, so that there is an absence of a substantial amount of freemoisture, i.e., purge, which is water and juices emitted outside of thefood/meat product. In general, there is an absence of a substantialamount of free moisture if the level of free moisture is from about 0 to2%, based on the weight of the meat product before cooking. Preferablythe amount of free moisture is from about 0 to 1%, more preferably, 0 to0.5%, and still preferably from 0 to 0.1 percent based on the weight ofthe meat product before cooking. As used herein, the phrases “meatpull-off” and “meat tear-off” refer to that portion of a cook-in meatproduct which is torn off of the meat product upon stripping the cook-infilm from the cooked meat product.

As used herein, the term “barrier”, and the phrase “barrier layer”, asapplied to films and/or film layers, are used with reference to theability of a film or film layer to serve as a barrier to one or moregases. In the packaging art, oxygen (i.e., gaseous O₂) barrier layershave included, for example, hydrolyzed ethylene/vinyl acetate copolymer(designated by the abbreviations “EVOH” and “HEVA”, and also referred toas “ethylene/vinyl alcohol copolymer”), polyvinylidene chloride,polyamide, polyester, polyacrylonitrile, etc., as known to those ofskill in the art.

As used herein, “EVOH” refers to ethylene vinyl alcohol copolymer. EVOHincludes saponified or hydrolyzed ethylene vinyl acetate copolymers, andrefers to a vinyl alcohol copolymer having an ethylene comonomer, andprepared by, for example, hydrolysis of vinyl acetate copolymers, or bychemical reactions with polyvinyl alcohol. The degree of hydrolysis ispreferably from about 50 to 100 mole percent; more preferably, fromabout 85 to 100 mole percent.

As used herein, the phrase “abuse layer”, as well as the phrase“puncture-resistant layer”, refer to an outer film layer and/or an innerfilm layer, so long as the film layer serves to resist abrasion,puncture, and other potential causes of reduction of package integrity,as well as potential causes of reduction of package appearance quality.

As used herein, the terms “lamination,” “laminate,” as well as thephrase “laminated film,” refer to the process, and resulting product,made by bonding together two or more layers of film or other materials.Lamination can be accomplished by joining layers with adhesives, joiningwith heat and pressure, with corona treatment, and even spread-coatingand extrusion-coating. The term laminate is also inclusive of coextrudedmultilayer films comprising one or more tie layers.

As used herein, the phrases “seal layer,” “sealing layer,” “heat seallayer,” and “sealant layer,” refer to an outer film layer, or layers,involved in the sealing of the film to itself, another film layer of thesame or another film, and/or another article which is not a film. Itshould also be recognized that in general, up to the outer 3 mils of afilm can be involved in the sealing of the film to itself or anotherlayer. With respect to packages having only fin-type seals, as opposedto lap-type seals, the phrase “sealant layer” generally refers to theinside film layer of a package, as well as supporting layers within 3mils of the inside surface of the sealant layer, the inside layerfrequently also serving as a food contact layer in the packaging offoods. In general, sealant layers employed in the packaging art haveincluded thermoplastic polymers, such as polyolefin, polyamide,polyester, and polyvinyl chloride.

As used herein, the term “oriented” refers to a polymer-containingmaterial which has been elongated (generally at an elevated temperaturecalled the orientation temperature), followed by being “set” in theelongated configuration by cooling the material while substantiallyretaining the elongated dimensions. This combination of elongation atelevated temperature followed by cooling causes an alignment of thepolymer chains to a more parallel configuration, thereby alteringvarious mechanical properties of the film. Upon subsequently heatingunrestrained, unannealed, oriented polymer-containing material to itsorientation temperature, heat shrinkage is produced almost to theoriginal dimensions, i.e., pre-elongation dimensions. The term“oriented,” is herein used with reference to oriented films, which canundergo orientation in any one or more of a variety of manners.

Orienting in one direction is referred to herein as “uniaxialorientation,” while orienting in two directions is referred to herein as“biaxial orientation.” In oriented plastic films, there can be internalstress remaining in the plastic sheet which can be relieved by reheatingthe film to a temperature above that at which it was oriented. Uponreheating such a film, the film tends to shrink back to the originaldimensions it had before it was oriented. Films which shrink upon beingheated are generally referred to as heat-shrinkable films.

As used herein, the phrase “orientation ratio” refers to themultiplication product of the extent to which the plastic film materialis oriented in several directions, usually two directions perpendicularto one another. Orientation in the machine direction is herein referredto as “drawing”, whereas orientation in the transverse direction isherein referred to as “stretching”. For films extruded through anannular die, stretching is obtained by “blowing” the film to produce abubble. For such films, drawing is obtained by passing the film throughtwo sets of powered nip rolls, with the downstream set having a highersurface speed than the upstream set, with the resulting draw ratio beingthe surface speed of the downstream set of nip rolls divided by thesurface speed of the upstream set of nip rolls. The degree oforientation is also referred to as the orientation ratio, also known asthe “racking ratio”.

As used herein, the term “monomer” refers to a relatively simplecompound, usually containing carbon and of low molecular weight, whichcan react to form a polymer by combining with itself or with othersimilar molecules or compounds.

As used herein, the term “comonomer” refers to a monomer which iscopolymerized with at least one different monomer in a copolymerizationreaction, the result of which is a copolymer.

As used herein, the term “polymer” refers to the product of apolymerization reaction, and is inclusive of homopolymers, copolymers,terpolymers, tetrapolymers, etc. In general, the layers of a film canconsist essentially of a single polymer, or can have additional polymerstogether therewith, i.e., blended therewith.

As used herein, the term “homopolymer” is used with reference to apolymer resulting from the polymerization of a single monomer, i.e., apolymer consisting essentially of a single type of repeating unit.

As used herein, the term “copolymer” refers to polymers formed by thepolymerization reaction of at least two different monomers. For example,the term “copolymer” includes the copolymerization reaction product ofethylene and an alpha-olefin, such as 1-hexene. The term “copolymer” isalso inclusive of, for example, the copolymerization of a mixture ofethylene, propylene, 1-hexene, and 1-octene. As used herein, the term“copolymerization” refers to the simultaneous polymerization of two ormore monomers. The term “copolymer” is also inclusive of randomcopolymers, block copolymers, and graft copolymers.

As used herein, the term “polymerization” is inclusive ofhomopolymerizations, copolymerizations, terpolymerizations, etc., andincludes all types of copolymerizations such as random, graft, block,etc. In general, the polymers, in the films used in accordance with thepresent invention, can be prepared in accordance with any suitablepolymerization process, including slurry polymerization, gas phasepolymerization, and high pressure polymerization processes.

As used herein, a copolymer identified in terms of a plurality ofmonomers, e.g., “propylene/ethylene copolymer”, refers to a copolymer inwhich either monomer may copolymerize in a higher weight or molarpercent than the other monomer or monomers. However, the first listedmonomer preferably polymerizes in a higher weight percent than thesecond listed monomer, and, for copolymers which are terpolymers,quadripolymers, etc., preferably the first monomer copolymerizes in ahigher weight percent than the second monomer, and the second monomercopolymerizes in a higher weight percent than the third monomer, etc.

As used herein, terminology employing a “/” with respect to the chemicalidentity of a copolymer (e.g., “an ethylenelalpha-olefin copolymer”),identifies the comonomers which are copolymerized to produce thecopolymer. As used herein, “ethylene alpha-olefin copolymer” is theequivalent of “ethylene/alpha-olefin copolymer.”

As used herein, copolymers are identified, i.e., named, in terms of themonomers from which the copolymers are produced. For example, the phrase“propylene(ethylene copolymer” refers to a copolymer produced by thecopolymerization of both propylene and ethylene, with or withoutadditional comonomer(s). As used herein, the phrase “mer” refers to aunit of a polymer, as derived from a monomer used in the polymerizationreaction. For example, the phrase “alpha-olefin mer” refers to a unitin, for example, an ethylene/alpha-olefin copolymer, the polymerizationunit being that “residue” which is derived from the alpha-olefin monomerafter it reacts to become a portion of the polymer chain, i.e., thatportion of the polymer contributed by an individual alpha-olefin monomerafter it reacts to become a portion of the polymer chain.

As used herein, the phrase “heterogeneous polymer” refers topolymerization reaction products of relatively wide variation inmolecular weight and relatively wide variation in compositiondistribution, i.e., polymers made, for example, using conventionalZiegler-Natta catalysts. Heterogeneous polymers are useful in variouslayers of the film used in the present invention. Such polymerstypically contain a relatively wide variety of chain lengths andcomonomer percentages.

As used herein, the phrase “heterogeneous catalyst” refers to a catalystsuitable for use in the polymerization of heterogeneous polymers, asdefined above. Heterogeneous catalysts are comprised of several kinds ofactive sites which differ in Lewis acidity and steric environment.Ziegler-Natta catalysts are heterogeneous catalysts. Examples ofZiegler-Natta heterogeneous systems include metal halides activated byan organometallic co-catalyst, such as titanium chloride, optionallycontaining magnesium chloride, complexed to trialkyl aluminum and may befound in patents such as U.S. Pat. No. 4,302,565, to GOEKE, et. al., andU.S. Pat. No. 4,302,566, to KAROL, et. al., both of which are herebyincorporated, in their entireties, by reference thereto.

As used herein, the phrase “homogeneous polymer” refers topolymerization reaction products of relatively narrow molecular weightdistribution and relatively narrow composition distribution. Homogeneouspolymers can be used in various layers of multilayer films useful in thepresent invention. Homogeneous polymers are structurally different fromheterogeneous polymers, in that homogeneous polymers exhibit arelatively even sequencing of comonomers within a chain, a mirroring ofsequence distribution in all chains, and a similarity of length of allchains, i.e., a narrower molecular weight distribution. Furthermore,homogeneous polymers are typically prepared using metallocene, or othersingle-site type catalysis, rather than using Ziegler Natta catalysts.

More particularly, homogeneous ethylene/alpha-olefin copolymers may becharacterized by one or more methods known to those of skill in the art,such as molecular weight distribution (M_(w)/M_(n)), compositiondistribution breadth index (CDBI), narrow melting point range, andsingle melt point behavior. The molecular weight distribution(M_(w)/M_(n)), also known as “polydispersity,” may be determined by gelpermeation chromatography. Homogeneous ethylene/alpha-olefin copolymerswhich can be used in the present invention preferably have anM_(w)/M_(n) of less than 2.7; more preferably from about 1.9 to 2.5;still more preferably, from about 1.9 to 2.3. The compositiondistribution breadth index (CDBI) of such homogeneousethylene/alpha-olefin copolymers will generally be greater than about 70percent. The CDBI is defined as the weight percent of the copolymermolecules having a comonomer content within 50 percent (i.e., plus orminus 50%) of the median total molar comonomer content. The CDBI oflinear polyethylene, which does not contain a comonomer, is defined tobe 100%. The Composition Distribution Breadth Index (CDBI) is determinedvia the technique of Temperature Rising Elution Fractionation (TREF).CDBI determination clearly distinguishes homogeneous copolymers (i.e.,narrow composition distribution as assessed by CDBI values generallyabove 70%) from VLDPEs available commercially which generally have abroad composition distribution as assessed by CDBI values generally lessthan 55%. TREF data and calculations therefrom for determination of CDBIof a copolymer is readily calculated from data obtained from techniquesknown in the art, such as, for example, temperature rising elutionfractionation as described, for example, in Wild et. al., J. Poly. Sci.Poly. Phys. Ed., Vol. 20, p.441 (1982). Preferably, the homogeneousethylene/alpha-olefin copolymers have a CDBI greater than about 70%,i.e., a CDBI of from about 70% to 99%. In general, the homogeneousethylene/alpha-olefin copolymers useful in the present invention alsoexhibit a relatively narrow melting point range, in comparison with“heterogeneous copolymers”, i.e., polymers having a CDBI of less than55%. Preferably, the homogeneous ethylene/alpha-olefin copolymersexhibit an essentially singular melting point characteristic, with apeak melting point (T_(m)), as determined by Differential ScanningColorimetry (DSC), of from about 60° C. to 105° C. Preferably thehomogeneous copolymer has a DSC peak T_(m) of from about 80° C. to 100°C. As used herein, the phrase “essentially single melting point” meansthat at least about 80%, by weight, of the material corresponds to asingle T_(m) peak at a temperature within the range of from about 60° C.to 105° C., and essentially no substantial fraction of the material hasa peak melting point in excess of about 115° C., as determined by DSCanalysis. DSC measurements are made on a Perk in Elmer System 7 ThermalAnalysis System. Melting information reported are second melting data,i.e., the sample is heated at a programmed rate of 10° C./min. to atemperature below its critical range. The sample is then reheated (2ndmelting) at a programmed rate of 10° C./min.

A homogeneous ethylene/alpha-olefin copolymer can, in general, beprepared by the copolymerization of ethylene and any one or morealpha-olefin. Preferably, the alpha-olefin is a C₃–C₂₀ alpha-monoolefin,more preferably, a C₄–C₁₂ alpha-monoolefin, still more preferably, aC₄–C₈ alpha-monoolefin. Still more preferably, the alpha-olefincomprises at least one member selected from the group consisting ofbutene-1, hexene-1, and octene-1, i.e., 1-butene, 1-hexene, and1-octene, respectively. Yet still more preferably, the alpha-olefincomprises octene-1, and/or a blend of hexene-1 and butene-1.

Processes for preparing and using homogeneous polymers are disclosed inU.S. Pat. No. 5,206,075, to HODGSON, Jr., U.S. Pat. No. 5,241,031, toMEHTA, and PCT International Application WO 93/03093, each of which ishereby incorporated by reference thereto, in its entirety. Furtherdetails regarding the production and use of homogeneousethylene/alpha-olefin copolymers are disclosed in PCT InternationalPublication Number WO 90/03414, and PCT International Publication NumberWO 93/03093, both of which designate Exxon Chemical Patents, Inc. as theApplicant, and both of which are hereby incorporated by referencethereto, in their respective entireties.

Still another species of homogeneous ethylene/alpha-olefin copolymers isdisclosed in U.S. Pat. No. 5,272,236, to LAI, et. al., and U.S. Pat. No.5,278,272, to LAI, et. al., both of which are hereby incorporated byreference thereto, in their respective entireties.

As used herein, the term “polyolefin” refers to any polymerized olefin,which can be linear, branched, cyclic, aliphatic, aromatic, substituted,or unsubstituted. Exemplary polyolefins include homopolymers of one ormore olefins, copolymers of olefin, copolymers of an olefin and annon-olefinic comonomer copolymerizable with the olefin such as vinylmonomers, modified polymers thereof, and the like. More specificexamples include polyethylene homopolymer, polypropylene homopolymer,polybutene, ethylene/alpha-olefin copolymer, propylene/alpha-olefincopolymer, butene/alpha-olefin copolymer, ethylene/vinyl acetatecopolymer, ethylene/vinyl alcohol copolymer, ethylene/ethyl acrylatecopolymer, ethylene/butyl acrylate copolymer, ethylene/methyl acrylatecopolymer, ethylene/acrylic acid copolymer, ethylene/methacrylic acidcopolymer, modified polyolefin resin, ionomer resin, polymethylpentene,etc. Modified polyolefin resin is inclusive of modified polymer preparedby copolymerizing the homopolymer of the olefin or copolymer thereofwith an unsaturated carboxylic acid, e.g., maleic acid, fumaric acid orthe like, or a derivative thereof such as the anhydride, ester or metalsalt or the like. It could also be obtained by incorporating into theolefin homopolymer or copolymer, an unsaturated carboxylic acid, e.g.,maleic acid, fumaric acid or the like, or a derivative thereof such asthe anhydride, ester or metal salt or the like.

As used herein, the phrases “ethylene alpha-olefin copolymer”, and“ethylene/alpha-olefin copolymer”, refer to such heterogeneous materialsas low density polyethylene (LDPE), medium density polyethylene (MDPE),linear low density polyethylene (LLDPE), and very low and ultra lowdensity polyethylene (VLDPE and ULDPE); as well as to such homogeneousethylene/alpha olefin copolymers as: metallocene-catalyzed EXACT (TM)linear homogeneous ethylene/alpha olefin copolymer resins obtainablefrom the Exxon Chemical Company, of Baytown, Tex., homogeneoussubstantially linear ethylene/alpha-olefin copolymers having long chainbranching (e.g., copolymers known as AFFINITY (TM) resins, and ENGAGE(TM) resins, available from the Dow Chemical Company, of Midland,Mich.), as well as TAFMER (TM) linear homogeneous ethylene/alpha-olefincopolymer resins obtainable from the Mitsui Petrochemical Corporation.Both the heterogeneous polymers and homogeneous polymers referred toabove generally include copolymers of ethylene with one or morecomonomers selected from C₄ to C₁₀ alpha-olefin such as butene-1 (i.e.,1-butene), hexene-1, octene-1, etc. While LDPE and MDPE are more highlybranched than LLDPE, VLDPE, ULDPE, EXACT (TM) resin, and TAFMER (TM)resin, this latter group of resins has a relatively large number ofshort branches rather than the longer branches present in LDPE and MDPE.AFFINITY (TM) resins and ENGAGE (TM) resins have a relatively largenumber of short branches in combination with a relatively small numberof long-chain branches. LLDPE has a density usually in the range of fromabout 0.91 grams per cubic centimeter to about 0.94 grams per cubiccentimeter.

In general, the ethylene/alpha-olefin copolymer comprises a copolymerresulting from the copolymerization of from about 80 to 99 weightpercent ethylene and from 1 to 20 weight percent alpha-olefin.Preferably, the ethylene alpha-olefin copolymer comprises a copolymerresulting from the copolymerization of from about 85 to 95 weightpercent ethylene and from 5 to 15 weight percent alpha-olefin.

As used herein, terms identifying polymers, such as “polyamide”,“polyester”, “polyurethane”, etc. are inclusive of not only polymerscomprising repeating units derived from monomers known to polymerize toform a polymer of the named type, but are also inclusive of comonomers,derivatives, etc. which can copolymerize with monomers known topolymerize to produce the named polymer. For example, the term“polyamide” encompasses both polymers comprising repeating units derivedfrom monomers, such as caprolactam, which polymerize to form apolyamide, as well as copolymers derived from the copolymerization ofcaprolactam with a comonomer which when polymerized alone does notresult in the formation of a polyamide. Furthermore, terms identifyingpolymers are also inclusive of “blends” of such polymers with otherpolymers of a different type.

As used herein, the phrase “modified polymer”, as well as more specificphrases such as “modified ethylene vinyl acetate copolymer”, and“modified polyolefin” refer to such polymers having an anhydridefunctionality, as defined immediately above, grafted thereon and/orcopolymerized therewith and/or blended therewith. Preferably, suchmodified polymers have the anhydride functionality grafted on orcopolymerized therewith, as opposed to merely blended therewith.

As used herein, the phrase “anhydride functionality” refers to any formof anhydride functionality, such as the anhydride of maleic acid,fumaric acid, etc., whether blended with one or more polymers, graftedonto a polymer, or copolymerized with a polymer, and, in general, isalso inclusive of derivatives of such functionalities, such as acids,esters, and metal salts derived therefrom.

Film useful in the present invention may be monolayer film or multilayerfilm. If multilayer, preferably the film has a total of from 1 to 20layers; more preferably, from 2 to 12 layers and still more preferably,from 4 to 9 layers. The multilayer film can have any total number oflayers and any total thickness desired, so long as the film provides thedesired properties for the particular packaging operation in which thefilm is used, e.g. O₂-barrier characteristics, free shrink shrinktension, optics, modulus, seal strength, etc.

As used herein, the phrases “inner layer” and “internal layer” refer toany layer, of a multilayer film, having both of its principal surfacesdirectly adhered to another layer of the film. As used herein, thephrase “inside layer” refers to an outer film layer, of a multilayerfilm packaging a product, or an article suitable for use in packaging aproduct (such as a bag or casing), which is closest to the product,relative to the other layers of the multilayer film. “Inside layer” alsois used with reference to the innermost layer of a plurality ofconcentrically arranged layers simultaneously coextruded through anannular die.

As used herein, the phrase “outside layer” refers to the outer layer, ofa multilayer film packaging a product, or an article suitable for use inpackaging a product (such as a bag or casing), which is furthest fromthe product relative to the other layers of the multilayer film.“Outside layer” also is used with reference to the outermost layer of aplurality of concentrically arranged layers simultaneously coextrudedthrough an annular die.

As used herein, the phrase “directly adhered”, as applied to filmlayers, is defined as adhesion of the subject film layer to the objectfilm layer, without a tie layer, adhesive, or other layer therebetween.In contrast, as used herein, the word “between”, as applied to a filmlayer expressed as being between two other specified layers, includesboth direct adherence of the subject layer between to the two otherlayers it is between, as well as including a lack of direct adherence toeither or both of the two other layers the subject layer is between,i.e., one or more additional layers can be imposed between the subjectlayer and one or more of the layers the subject layer is between.

As used herein, the term “core”, and the phrase “core layer”, as appliedto multilayer films, refer to any inner film layer which has a primaryfunction other than serving as an adhesive (i.e., tie layer, whichadheres two incompatible layers) for adhering two layers to one another.Usually, the core layer or layers provide the multilayer film with adesired level of strength, i.e., modulus, and/or optics, and/or addedabuse resistance, and/or specific impermeability.

As used herein, the phrase “tie layer” refers to any inner film layerhaving the primary purpose of adhering two layers to one another. Tielayers can comprise any polymer having a polar group thereon, or anyother polymer which provides sufficient interlayer adhesion to adjacentlayers comprising otherwise nonadhering polymers. Suitable polymersinclude polyolefins, such as those incorporating acids, esters,anhydrides or salts of carboxylic acids; and polar, non-polyolefinicmaterials such as polyesters, ethylene vinyl alcohol copolymer, etc.

As used herein, the phrase “skin layer” refers to an outside layer of amultilayer film in packaging a product, this skin layer being subject toabuse.

As used herein, the phrase “bulk layer” refers to any layer of a filmwhich is present for the purpose of increasing the abuse-resistance,toughness, modulus, etc., of a multilayer film. Bulk layers generallycomprise polymers which are inexpensive relative to other polymers inthe film which provide some specific purpose unrelated toabuse-resistance, modulus, etc.

The names “first layer”, “second layer”, as used herein, are generallyindicative of the manner in which a multilayer film structure is builtup. That is, in general, the first layer can be present without any ofthe additional layers described, or the first and second layers can bepresent without any of the additional layers described, etc.

As used herein, the term “extrusion” is used with reference to theprocess of forming continuous shapes by forcing a molten plasticmaterial through a die, followed by cooling or chemical hardening.Immediately prior to extrusion through the die, the relativelyhigh-viscosity polymeric material is fed into a rotating screw ofvariable pitch, i.e., an extruder, which forces the polymeric materialthrough the die.

As used herein, the term “coextrusion” refers to the process by whichthe outputs of two or more extruders are brought smoothly together in afeed block, to form a multilayer stream that is fed to a die to producea layered extrudate. Coextrusion can be employed in film blowing, sheetand flat film extrusion, blow molding, and extrusion coating.

As used herein, the phrase “machine direction”, herein abbreviated “MD”,refers to a direction “along the length” of the film, i.e., in thedirection of the film as the film is formed during extrusion and/orcoating. As used herein, the phrase “transverse direction”, hereinabbreviated “TD”, refers to a direction across the film, perpendicularto the machine or longitudinal direction.

As used herein, the phrase “free shrink” refers to the percentdimensional change in a 10 cm×10 cm specimen of film, when shrunk at185° F., with the quantitative determination being carried out accordingto ASTM D 2732, as set forth in the 1990 Annual Book of ASTM Standards,Vol. 08.02, pp. 368–371, which is hereby incorporated, in its entirety,by reference thereto.

If heat-shrinkable, the film article preferably has a free shrink offrom about 5–70 percent in at least one direction (i.e., thelongitudinal (L) or transverse (T) direction) at 185° F.; morepreferably, from about 10–50 percent at 185° F.; and, still morepreferably, from about 15–35 percent at 185° F. For conversion to bagsand casings, preferably the film article is biaxially oriented, andpreferably the film has a free shrink, at 185° F., of at least 10percent in each direction (L and T); more preferably, at least 15percent in each direction. For casing end use, preferably the film has atotal free shrink (L+T) of from about 30 to 50 percent at 185° F. Forbag end-use, preferably the total free shrink is even higher, i.e.,preferably at least 50% (L+T), more preferably from 50 to 120%. For useas a thermoformed article, preferably the film has a total free shrink(before thermoforming) of from 0 to 10% (L+T), more preferably, from 1to 5 percent (L+T). Alternately, the oriented film article can beheat-set. Heat-setting can be done at a temperature from about 60–200°C., more preferably 70–150° C. and, even more preferably, 80–90° C.

In general, the multilayer film used in the present invention can haveany total thickness desired, so long as the film provides the desiredproperties for the particular packaging operation in which the film isused. Preferably, the film used in the present invention has a totalthickness (i.e., a combined thickness of all layers), of from about 0.3to 15 mils (1 mil equals 0.001 inch); more preferably, from about 1 to10 mils; and still more preferably, from 1.5 to 8 mils. For shrinkablecasings, the range from 1.5–3 mils is even more preferred while forlaminates used in cook-in packaging, the range from 4–8 mils is evenmore preferred.

The film article preferably has a modulus ranging from about 5,000 to500,000 psi, more preferably from about 10,000 to 300,000 psi, and mostpreferably from about 40,000 to 200,000 psi. The food-contact layeritself may have a modulus ranging from about 3,000 to 500,000 psi.

Exemplary films which can be coated with a coating formulationcomprising a binder and an additive in accordance with the presentinvention, which can thereafter be used in accordance with the presentinvention, include the films disclosed in: (a) U.S. Ser. No. 669,728,filed Jun. 26, 1996, in the name of Ram K. Ramesh; (b) U.S. Ser. No.08/539,919, filed Oct. 6, 1995, in the name of Ram K. Ramesh; U.S. Ser.No. 57,587, in the name of Lorenzo et al, filed Dec. 22, 1995; U.S. Pat.No. 4,287,151, to ESAKOV, et. al., issued Sep. 1, 1981; and U.S. Ser.No. 617,720, in the name of Beckwith et al., filed Apr. 1, 1996. Each ofthese documents is hereby incorporated in its entirety, by referencethereto. Film No. 1 and Film No. 2, described in detail below, arepreferred films for subsequent coating with a coating formulation inaccordance with the present invention.

The following multilayer film structures films according to the presentinvention, as the “coating” layer contains the combination of additiveand binder present in the film of the present invention. In thefollowing film structures, the individual layers are shown in the orderin which they would appear in the film:

SEAL/FOOD-CONTACT (coating) ABUSE/SEAL/FOOD-CONTACT (coating)ABUSE/BARRIER/SEAL/FOOD-CONTACT (coating)ABUSE/TIE/BARRIER/TIE/SEAL/FOOD-CONTACT (coating)ABUSE/TIE/BARRIER/TIE/BULK/SEAL/FOOD-CONTACT (coating)ABUSE/BULK/TIE/BARRIER/TIE/BULK/SEAL/FOOD-CONTACT (coating)ABUSE/BULK/TIE/BARRIER/MOISTURE/TIE/BULK/SEAL/ FOOD-CONTACT (coating)

The foregoing representative film structures are intended to beillustrative only and not limiting in scope.

The layer which is to be coated with the coating formulation (whichcontains the binder and the additive) comprises a thermoplastic polymer.Preferably, the thermoplastic polymer comprises at least one memberselected from the group consisting of polyolefin, polyamide, polyester,polyvinylchloride, polyacrylonitrile, and polyurethane. Preferably, theheat seal layer has a thickness of from about 0.1 to 4 mils; morepreferably, from about 0.2 to about 1 mil; and, still more preferably,from about 0.3 to 0.8 mils. In embodiments in which the packaged productcomprises a bag in which a meat product is packaged and thereaftercooked, the seal layer preferably comprises at least 10% of a totalweight of the multilayer film; more preferably, from about 12% to 25% byweight of the total multilayer film. In the case of oriented films usedto make bags, it is preferred that the seal layer has a thickness lessthan 35% by weight of the multilayer film; more preferably from about 5to 25% by weight of the multilayer film; still more preferably, fromabout 10 to 20% by weight of the multilayer film; seal layers thickerthan 35% can cause problems during the orientation process.

In the film according to the present invention, the outsideheat-resistant and abuse layer preferably has a thickness of from about0.1 to 5 mils; more preferably, from 0.2 to 3 mil; still morepreferably, from 0.3 to 2 mil; and yet still more preferably, about 0.5to 1.5 mil. Preferably, the outside heat-resistant and abuse layercomprises at least one member selected from the group consisting ofpolyolefin, polystyrene, polyamide, polyester, polymerized ethylenevinyl alcohol, polyvinylidene chloride, polyether, polyurethane,polycarbonate, and starch-containing polymer; more preferably, at leastone member selected from the group consisting of polyolefin; still morepreferably, at least one member selected from the group consisting ofethylene/alpha-olefin copolymer, propylene/alpha-olefin copolymer,butene/alpha-olefin copolymer, ethylene/unsaturated ester copolymer, andethylene/unsaturated acid copolymer; and still more preferably, a blendof 80 weight percent ethylene vinyl acetate copolymer (having 6.5 weightpercent vinyl acetate) with 20 weight percent high density polyethylene.

The film according to the present invention optionally (and preferably)contains an O₂-barrier layer. The O₂-barrier layer is an inner layerwhich is between the seal layer and the abuse layer. The O₂-barrierlayer comprises a polymer having relatively high O₂-barriercharacteristics. Preferably, the O₂-barrier layer has a thickness offrom about 0.05 to 2 mils; more preferably, from 0.05 to 0.5 mil; yetstill more preferably, from 0.1 to 0.3 mil; and even yet still morepreferably, from about 0.12 to 0.17 mils. Preferably, the O₂-barrierlayer comprises at least one member selected from the group consistingof polymerized ethylene vinyl alcohol (EVOH), polyvinylidene chloride,polyamide, polyester and polyalkylene carbonate; more preferably, atleast one member selected from the group consisting of EVOH andpolyamide; still more preferably, EVOH; yet still more preferably, EVOHhaving about 44 mole percent ethylene mer.

The film according to the present invention may optionally furthercontain a tie layer, also referred to by those of skill in the art as anadhesive layer. The function of a tie layer is to adhere film layerswhich are otherwise incompatible in that they do not form a strong bondduring coextrusion or extrusion coating. Tie layer(s) suitable for usein the film according to the present invention have a relatively highdegree of compatibility with (i.e., affinity for) the O₂-barrier layersuch as polymerized EVOH, polyamide, etc., as well as a high degree ofcompatibility for non-barrier layers, such as polymerizedethylene/alpha-olefin copolymers. In general, the composition, number,and thickness of the tie layer(s) is as known to those of skill in theart. Preferably, the tie layer(s) each have a thickness of from about0.01 to 2 ml's; more preferably, from 0.05 to 0.3 mil; and, still morepreferably, from about 0.1 to 0.25 mils. Preferably, the tie layer(s)each comprise at least one member selected from the group consisting ofmodified polyolefin ionomer, ethylene/unsaturated acid copolymer,ethylene/unsaturated ester copolymer, polyamide, and polyurethane; morepreferably, at least one member selected from the group consisting ofmodified polyolefin and polyurethane; still more preferably, at leastone member selected from the group consisting of modifiedethylene/alpha-olefin copolymer, modified ethylene/unsaturated estercopolymer, and modified ethylene/unsaturated acid copolymer, even yetstill more preferably, anhydride-grafted linear low densitypolyethylene.

Films according to the present invention may further comprises an innerlayer which provides the multilayer film with desired strength, bulk,abuse, shrink, balance (i.e., anti-curl), elastic recovery, and/oroptical characteristics, and preferably comprises a polymer havingrelatively low cost while providing these attributes. Such layerspreferably have a thickness of from about 0.1 to 3 mils; morepreferably, from 0.2 to 1.5 mil; still more preferably, from 0.3 to 1mil; and yet still more preferably, from about 0.50 to 0.80 mils.Preferred polymers in such inner layers comprise at least one memberselected from the group consisting of polyolefin, polystyrene,polyamide, polyester, polymerized ethylene vinyl alcohol, polyvinylidenechloride, polyether, polyurethane, polycarbonate, and starch-containingpolymer; more preferably, at least one member selected from the groupconsisting of ethylene/alpha-olefin copolymer, propylene/alpha-olefincopolymer, butene/alpha-olefin copolymer, ethylene/unsaturated estercopolymer, and ethylene/unsaturated acid copolymer; still morepreferably, ethylene/unsaturated ester copolymer.

FIG. 1 illustrates a process for making a “substrate film” which canthereafter be coated so that it becomes a film in accordance with thepresent invention. In the process illustrated in FIG. 1, variouspolymeric formulations solid polymer beads (not illustrated) are fed toa plurality of extruders (for simplicity, only one extruder isillustrated). Inside extruders 10, the polymer beads are degassed,following which the resulting bubble-free melt is forwarded into diehead 12, and extruded through an annular die, resulting in tubing tape14 which is preferably from about 15 to 30 mils thick, and preferablyhas a lay-flat width of from about 2 to 10 inches.

After cooling or quenching by water spray from cooling ring 16, tubingtape 14 is collapsed by pinch rolls 18, and is thereafter fed throughirradiation vault 20 surrounded by shielding 22, where tubing 14 isirradiated with high energy electrons (i.e., ionizing radiation) fromiron core transformer accelerator 24. Tubing tape 14 is guided throughirradiation vault 20 on rolls 26. Preferably, tubing tape 14 isirradiated to a level of from about 40–100 kGy, resulting in irradiatedtubing tape 28. Irradiated tubing tape 28 is wound upon windup roll 30upon emergence from irradiation vault 20, forming irradiated tubing tapecoil 32.

After irradiation and windup, windup roll 30 and irradiated tubing tapecoil 32 are removed and installed as unwind roll 34 and unwind tubingtape coil 36, on a second stage in the process of making the tubing filmas ultimately desired. Irradiated tubing 28, being unwound from unwindtubing tape coil 36, is then passed over guide roll 38, after whichirradiated tubing 28 is passed through hot water bath tank 40 containinghot water 42. Irradiated tubing 28 is then immersed in hot water 42(preferably having a temperature of about 85° C. to 99° C.) for a periodof about 20 to 60 seconds, i.e., for a time period long enough to bringthe film up to the desired temperature for biaxial orientation.Thereafter, hot, irradiated tubular tape 44 is directed through niprolls 46, and bubble 48 is blown, thereby transversely stretching hot,irradiated tubular tape 44 so that oriented film tube 50 is formed.Furthermore, while being blown, i.e., transversely stretched, nip rolls52 have a surface speed higher than the surface speed of nip rolls 46,thereby resulting in longitudinal orientation. As a result of thetransverse stretching and longitudinal drawing, oriented film tube 50 isproduced, this blown tubing preferably having been both stretched in aratio of from about 1:1.5 to 1:6, and drawn in a ratio of from about1:1.5 to 1:6. More preferably, the stretching and drawing are eachperformed at a ratio of from about 1:2 to 1:4. The result is a biaxialorientation of from about 1:2.25 to 1:36, more preferably, 1:4 to 1:16.While bubble 48 is maintained between pinch rolls 46 and 52, blowntubing 50 is collapsed by converging pairs of parallel rollers 54, andthereafter conveyed through pinch rolls 52 and across guide roll 56, andthen rolled onto wind-up roll 58. Idler roll 60 assures a good wind-up.

The resulting multilayer film can be used to form bags, casings,thermoformed articles and lidstocks therefor, etc., which, in turn, canbe used for the packaging of protein-containing products (especiallymeat products) in accordance with the present invention. Examples 1–9,below, provide additional details on some of the preferred films, theiruse in the packaging of a meat product, and the unexpected resultsobtained therefrom.

FIG. 2 illustrates bag 62 in lay-flat configuration. Bag 62 is made fromfilm 64, and has open top 66, as well as bottom 68 closed by end-seal70. Bag 62 has a coating on the inside surface thereof (not illustrated)the coating being the inside layer of film 64. An uncookedprotein-containing food product, such as a meat product, is placedinside bag 62, with sealed and evacuated bag 62 thereafter beingevacuated and sealed, resulting in packaged meat product 72 illustratedin FIG. 3. The product, which is surrounded by the film, is thereaftercooked while remaining in the film. During cooking, the additive andbinder are transferred from the bag to the outer surface of the cookedproduct, in accordance with the present invention.

FIG. 4 illustrates another embodiment of a packaged product 74 of thepresent invention, the product being packaged in a casing closed by apair of clips 76 at each end thereof, with only one clip beingillustrated in the perspective view of FIG. 4. Film 78, used to packagethe meat product inside the casing, can be, for example, Film No. 1 orFilm No. 2, discussed in detail below.

FIG. 5A illustrates a first cross-sectional view of packaged product 74,i.e., taken through line 5—5 of FIG. 4. FIG. 5A represents across-sectional view of a lap-sealed casing comprising film 78 having acoated inside surface region 80, with an uncoated portion heat sealed tooutside surface 82 at heat seal 84, the heat seal being located where afirst film region overlaps a second film region.

FIG. 5B illustrates an alternative cross-sectional view of packagedproduct 74, i.e., also taken though line 5—5 of FIG. 4. FIG. 5Brepresents a cross-sectional view of a butt-sealed backseamed casingcomprising film 78 having a coated inside surface region 86. Casing film78 is heat sealed to butt-seal tape 88. Casing film 78 has insidesurface 86 and outside surface 90. Outside surface 90 is heat-sealed tobutt-seal tape 88 at seals 87 and 89, where each of the edges of casingfilm 78 are abutted in close proximity to one another. In this manner,butt-seal tape 88 provides a longitudinal seal along the length ofbutt-sealed casing film 78. Although butt-seal tape 88 can be made froma monolayer film or a multilayer film, preferably butt-seal tape 88 ispreferably made from a multilayer film.

FIG. 5C illustrates a cross-sectional view of a third alternative ofpackaged product 74, i.e., again taken through line 5—5 of FIG. 4. FIG.5C represents a cross-sectional view of a fin-sealed casing comprisingfilm 78 having a coated inside surface region 92. Along the edges of theinside surface of casing film 78 are two uncoated regions which are heatsealed to one another at seal 94, which forms a “fin” which extends fromcasing 74.

FIG. 6 illustrates yet another embodiment of a packaged cooked meatproduct 96, which is in accordance with the present invention. Theproduct, a cooked meat product, is packaged in a heat-sealed,thermoformed web having a lidstock web sealed thereto, with the meatproduct being cooked while being within the sealed thermoformed package.A portion of each of the films, i.e, the thermoformed web and thelidstock film, have the binder/additive coating thereon, for contactwith the product and transfer to the product during cook-in. In thepackaging process resulting in the packaged product illustrated in FIG.6, a forming web and a non-forming web can be fed from two separaterolls, with the forming web being fed from a roll mounted on the bed ofthe machine for forming the package “pocket,” i.e., the product cavity.The non-forming (lidstock) web is usually fed from a top-mounted arborfor completing the airtight top seal of the package. Each web has itsmeat-contact/sealant surface oriented towards the other, so that at thetime of sealing, the sealant surfaces face one another. The forming webis indexed forward by transport chains, and the previously sealedpackage pulls the upper non-forming web along with the bottom web as themachine indexes.

The first step in the packaging process is the formation of the productcavity in the forming web. The cavity forming is a three-step process:index—heat—form. While one cavity is being formed, the web for the nextcavity is undergoing preheating before being indexed over thepocket-forming die. To accomplish this, the forming web is heated from70° C. to 80° C. by being pressed against a contact-type heater by meansof vacuum. The forming web is then formed by use of compressed air orvacuum, or both. Compressed air pushes the heated film into the diecavity from above and, in turn, vacuum pressure pulls the film intoshape from within the die. A plug is used to assist the movement of theheated film into the die cavity.

After forming, the transport chains carry the empty pocket to theloading station where the product is either hand loaded or pumped intothe cavity. The transport chains then carry the loaded product to thevacuum and sealing station.

The sealing process is a series of operations occurring simultaneouslyor with a slight overlap. Once the top film is in place over the, filledcavity, the sealing chamber closes. Package air is exhausted between thetop and bottom films. The upper chamber, or lid, employs a heated sealplate set at from 302° F. to 338° F., which bonds the non-forming weband the forming web together.

The vacuum in the seal die balances chamber pressures, and ensures thatno air is trapped between the product and the forming web. The sealingdiaphragms, empty of air, are now filled with compressed air. Thispresses the heated sealing plate against the upper film, compressing theheat-sealable surfaces of the two webs between the sealing plate and theT-rubber sealing gasket. The heat and pressure of the sealing platecauses the two surfaces of the films to bond together, sealing theproduct in a vacuum environment. Approximately 0.4 to 0.5 seconds aftersealing ends, the upper and lower chambers are vented to the atmosphere,causing the top and bottom films to collapse around the product. Now,the sealing diaphragms evacuate and the sealing plate moves back up.Outside air rushes into the chambers. When the air pressures areequalized, the die bottom can move down, allowing the package to beindexed out of the seal station.

The sealed package is then separated from the web by way of a contourknife system. The packages are conveyed through a hot water (205° F.)shrink tunnel. The packages are placed on racks and cooked in a highhumidity oven. The product is then chilled and available for shipping orfor further processing, which may involve stripping the package off ofthe product.

The polymer components used to fabricate multilayer films according tothe present invention may also contain appropriate amounts of otheradditives normally included in such compositions. These include slipagents such as talc, antioxidants, fillers, pigments and dyes, radiationstabilizers, antistatic agents, elastomers, and the like additives, asknown to those of skill in the art of packaging films.

Although film useful in the present invention need not always beirradiated, in at least one preferred embodiment, the film isirradiated. In the irradiation process, the film is subjected to anenergetic radiation treatment, such as corona discharge, plasma, flame,ultraviolet, X-ray, gamma ray, beta ray, and high energy electrontreatment, which may alter the surface of the film and/or inducecross-linking between molecules of the irradiated material. Theirradiation of polymeric films is disclosed in U.S. Pat. No. 4,064,296,to BORNSTEIN, et. al., which is hereby incorporated in its entirety, byreference thereto. BORNSTEIN, et. al. discloses the use of ionizingradiation for crosslinking polymer present in the film.

Radiation dosages are referred to herein in terms of the radiation unit“RAD”, with one million RADS, also known as a megarad, being designatedas “MR”, or, in terms of the radiation unit kiloGray (kGy), with 10kiloGray representing 1 MR, as is known to those of skill in the art. Toproduce crosslinking, the polymer is subjected to a suitable radiationdosage of high energy electrons, preferably using an electronaccelerator, with a dosage level being determined by standard dosimetrymethods. A suitable radiation dosage of high energy electrons is in therange of up to about 16–166 kGy, more preferably about 30–139 kGy, andstill more preferably, 50–100 kGy. Preferably, irradiation is carriedout by an electron accelerator and the dosage level is determined bystandard dosimetry methods. However, other accelerators such as a VanderGraff or resonating transformer may be used. The radiation is notlimited to electrons from an accelerator since any ionizing radiationmay be used. A preferred amount of radiation is dependent upon the filmand its end use.

As used herein, the phrases “corona treatment” and “corona dischargetreatment” refer to subjecting the surfaces of thermoplastic materials,such as polyolefins, to corona discharge, i.e., the ionization of a gassuch as air in close proximity to a film surface, the ionizationinitiated by a high voltage passed through a nearby electrode, andcausing oxidation and other changes to the film surface, such as surfaceroughness. As used herein, the term corona treatment also refers to allforms of plasma treatment.

Corona treatment of polymeric materials is disclosed in U.S. Pat. No.4,120,716, to BONET, issued Oct. 17, 1978, herein incorporated in itsentirety by reference thereto. BONET discloses improved adherencecharacteristics of the surface of polyethylene by corona treatment, tooxidize the polyethylene surface. U.S. Pat. No. 4,879,430, to HOFFMAN,also hereby incorporated in its entirety by reference thereto, disclosesthe use of corona discharge for the treatment of plastic webs for use inmeat cook-in packaging, with the corona treatment of the inside surfaceof the web to increase the adhesion of the meat to the adhesion of themeat to the proteinaceous material.

Packaged products in accordance with the present invention include beef,turkey, pork, fish, and meat substitutes.

The invention is illustrated by the following examples, which areprovided for the purpose of representation, and are not to be construedas limiting the scope of the invention. Unless stated otherwise, allpercentages, parts, etc. are by weight.

Preparation of Film No. 1

A 5¾″ wide (lay-flat dimension) tube, called a “tape”, was produced bythe coextrusion process described above and illustrated in FIG. 1,wherein the film cross-section (from inside to outside of the tube) wasas follows:

TABLE 1 Layer Layer Function(s) Thickness and Arrangement LayerComposition (mils) seal blend of 70% LLDPE#1 and 30% 3.2 EAA#1 strengthblend of 80% EVA#1 and 20% 3.5 HDPE#1 tie anhydride-grafted LLDPE#2 0.9O₂-barrier 100% EVOH 1.0 strength and blend of 50% Nylon#1 and 50% 1.7moisture barrier Nylon#2 tie anhydride-grafted LLDPE#2 1.6 strength andbalance blend of 70% EVA#1 and 30% EAA#1 3.1 outside LLDPE#1 2.8

wherein:

LLDPE#1 was DOWLEX® 2244A, linear low density polyethylene, obtainedfrom Dow Plastics, of Freeport, Tex.;

EAA#1 was PRIMARCOR® 1410 ethylene/acrylic acid copolymer obtained fromDow Plastics, of Freeport, Tex. This copolymer had a acrylic acidcontent of 9.5% by wt. and a melt index of 1.5;

EVA#1 was PE 5269T (TM) ethylene vinyl acetate copolymer, obtained fromChevron Chemical Company, of Houston, Tex.;

HDPE#1 was FORTIFLEX® J60-500C-147 high density polyethylene, obtainedfrom Solvay Polymers, Inc., Deer Park, Tex.;

LLDPE#2 was TYMOR® 1203 linear low density polyethylene having ananhydride functionality grafted thereon, obtained from MortonInternational, of Chicago, Ill.;

EVOH was EVAL® LC-E105A polymerized ethylene vinyl alcohol, obtainedfrom Eval Company of America, of Lisle, Ill.;

NYLON#1 was ULTRAMID® B4 polyamide 6, obtained from BASF corporation ofParsippany, N.J.;

NYLON#2 was GRILON® CF6S polyamide 6/12, obtained from EMS-AmericanGrilon Inc., of Sumter, S.C.;

All the resins were coextruded at between 380° F. and 500° F., and thedie was heated to approximately 420° F. The extruded tape was cooledwith water and flattened, the flattened width being 5¾ inches wide in alay flat configuration. The tape was then passed through a scanned beamof an electronic cross-linking unit, where it received a total passageof about 64 kilo grays (kGy). After irradiation, the flattened tape waspassed through hot water (approximately 206° F. to 210° F.) for about 20seconds. The resulting heated tape was inflated into a bubble andoriented into a film tubing having a lay-flat width of 16½ inches and atotal thickness of about 2.4 mils. The bubble was stable and the opticsand appearance of the film were good. The film tubing was determined tohave about 20% free shrinkage in the longitudinal direction and about30% free shrinkage in the transverse direction, when immersed in hotwater for about 10 minutes, the hot water being at a temperature of 185°F., i.e., using ASTM method D2732-83. The resulting tubing was slit intofilm.

Preparation of Film No. 2

A 2.4 mil film was made slitting a tubing made by the process of FIG. 1,the tubing having the following structure:

TABLE 2 Layer Layer Function(s) Thickness and Arrangement LayerComposition (mils) inside and seal blend of Nylon#3 (50%) 0.48 andNylon#2 (50%) bulk blend of 80% EVA#1 and 20% EAO#1 0.50 tieanhydride-grafted LLDPE#2 0.15 O₂-barrier EVOH 0.15 tieanhydride-grafted LLDPE#2 0.15 abuse and bulk blend of 80% EVA#1 and 20%0.97 LLDPE#3

NYLON#3 was VESTAMID (TM) Z7319 polyamide 12, obtained from HulsAmerica, Inc., of Piscataway, N.J.;

LLDPE#3 was DOWLEX® 2045.03 linear low density polyethylene, obtainedfrom Dow Plastics, of Freeport, Tex.;

EAO#1 was EXACT 4011 (TM) homogeneous ethylene/alpha-olefin copolymer,obtained from the Exxon Chemical Company, of Baytown, Tex.; otherwise,each of the resins was as identified in Film No. 1, above.

Preparation of Coating Formulation No. 1

This example demonstrates preparation of a typical coating formulation,the film coating process, the backseaming of the film to make casing andcooking of the meat for color transfer from casing to the meat. Thecoating formulation was prepared by the following procedure:

Liquid Smoke #1 33.3 grams Hydroxypropyl starch #1   35 grams Caramel #1  98 grams Glycerol #1  3.5 grams Water 85.7 grams

Hydroxypropyl Starch #1 was PURE COTE™ B790 hydroxypropyl starch,obtained from Grain Processing Corporation, of Muscatine, Iowa;

Liquid Smoke #1 was Charsol Select® 24 liquid smoke solution having a pHof approximately 2.4, obtained from Red Arrow Products Co., Inc., ofManitowoc, Wis.;

Caramel #1 was Caramel 252™, obtained from D.D. Williamson and Company,Inc., of Louisville, Ky.;

Hydroxypropyl Starch #1 was slowly added to a stirred solution of LiquidSmoke #1 and water, while the solution was heated to a temperature ofapproximately 150° F. The temperature of the stirred mixture was thenmaintained at about 150° F. for about ½ hour, whereafter the viscosityof the mixture dropped substantially due to the hydration of thehydroxypropyl starch. The mixture was then cooled to room temperature,and the Caramel #1 and Glycerol #1 were added to the mixture.

EXAMPLE 1 Coated Film 1A: Coating, Backseaming, Stuffing, Sealing,Cooking, and Color Transfer

Coating Formulation No. 1 was used to coat Film No. 1. Prior to thecoating process, the film was corona treated on the food-contact side(i.e., the layer comprising 70% LLDPE #1 and 30% EAA#1). The coating wasapplied using a gravure roll in such a manner that approximately oneinch along each of the machine-direction edges of the film remaineduncoated. The resulting coated film was then slit on one side tocompletely remove one of the uncoated edge portions of the film. Theremaining coated film (having one uncoated edge region) was foldedlongitudinally, i.e. along its length, about a forming shoe, withopposed edges being joined by applying a heat seal longitudinally overthe overlap to form a lap seal, done in intermittent, i.e.,semi-continuous manner (commonly referred to as backseaming). Thebackseaming was done in such a manner that for the overlap, the uncoatedpart of the film was the outside surface of the resulting backseamedcasing. The sealing was carried out so that the resulting tubing hadalmost no uncoated region on its inside surface. This casing was thenplaced on a shirring tube, clipped at one end and filled with uncookedturkey meat from the open end, followed by being clipped and cut on theopposite end.

The additive (i.e., caramel and liquid smoke) transfer evaluation wasmade using a turkey breast meat batter. To 40 pounds (lb.) of diced orground meat was added:

-   -   22.6 lb. of water,    -   1.3 lb. of salt,    -   1.3 lb. of carragean,    -   0.3 lb. of sodium polyphosphate, and    -   1.0 lb. of starch.

The meat and the added ingredients were blended in a vacuum mixer at 4°C. for at least 45 minutes. The backseamed casing was filled with themeat batter using a mechanical piston stuffer and sealed with a TipperClipper® machine obtained from the Tipper Tie Inc. of Apex. NorthCarolina. The filled and clipped casings (i.e., chubs) typicallymeasured 23 to 25 cm in circumference and 20 to 40 cm in length.

The meat was then cooked for several hours in a high humidityenvironment, i.e., beginning at 145° F. and ending at 170° F. Afterchilling, the meat was evaluated for color transfer. Upon stripping thefilm from the meat, there was no meat pull-off, the level of purge wasvery low, and it was found that the color had been completelytransferred to the meat.

Product evaluation included uniformity of the color transfer, purgeloss, gel formation, and color smearing. Purge loss was measured byweighing the chub after cooking and cooling to about 3° C., removing thecasing and blotting both the casing and meat surface to remove any freemoisture, and then weighing the meat plus the casing. The differencebetween the two weights was the weight of purge lost from the productduring cooking. The uniformity of color transfer, gel formation andcolor smearing were subjective observations. Unpredictably andsurprisingly: (a) the coating remained intact during the shirringprocess; (b) the distribution of the additives (liquid smoke andcaramel) was uniform on the surface of the cooked meat (neither mottlednor smeared), and (c) the film was clear and what little purge there wasnot highly colored.

EXAMPLE 2 Coated Film 1B: Coating, Backseaming, Stuffing, Sealing,Cooking, and Color Transfer

The coating of the other side of Film No. 1 demonstrated that thecoating could be carried out on a 100% LLDPE surface. The 100% LLDPEsurface of Film No. 1 was corona treated and coated by the methoddescribed immediately above. The resulting coated film was then alsobackseamed as described immediately above, resulting in a backseamedcasing having the coating on the inside surface thereof.

A packaged product was made as in Example 1, with the meat also beingcooked as described in Example 1. Unpredictably and surprisingly: (a)the coating remained intact during the shirring process; (b) thedistribution of the additives (liquid smoke and caramel) was uniform onthe surface of the cooked meat (neither mottled nor smeared), and (c)the film was clear and what little purge there was not highly colored.

EXAMPLE 3 Film Coating Backseaming, Stuffing, Sealing, Cooking, andColor Transfer

The coating of Film 2 demonstrated that the coating could be carried outon a polar surface such as polyamide. Before coating, corona treatmentwas applied to the outer layer containing of 50% Nylon #1 and 50% Nylon#2. The coating of Film No. 2 was carried out in the manner as generallydescribed for the coating of Film 1. The coating was applied to theouter surface which had been corona treated. The resulting coated filmwas then backseamed as described above, resulting in a lap-sealedbackseamed casing. This backseamed casing was then clipped at one endand filled with uncooked turkey meat from the open end, and clippedagain. The meat was then cooked in a high humidity environment from 145°F. to 170° F. for several hours. After chilling the meat was evaluatedfor color transfer. Upon stripping the film from the meat, it was foundthat the color had been completely transferred to the meat.Unpredictably and surprisingly: (a) the coating remained intact duringthe shirring process; (b) the distribution of the additives (liquidsmoke and caramel) was uniform on the surface of the cooked meat(neither mottled nor smeared), and (c) the film was clear and whatlittle purge there was not highly colored.

Thus, in each of Examples 1, 2, and 3, it was demonstrated thatsuccessful coating and color transfer could be made for both sides ofFilm 1, and the polyamide side of Film 2. More particularly, it wasdemonstrated that successful coating and color transfer could beachieved using either a non-polar outer film surface, such as is presentfor an outer layer of LLDPE, as well as a more polar outer film surface,such as is present for an outer layer consisting of polyamide.

EXAMPLE 4 Corona Treatment Can Improve Performance of Coated Film

In some cases corona treatment may can improve the successful transferof the additive from the coated film to a food product, such as meat. InFilm 1, the layer containing 70% LLDPE #1 and 30% EAA#1 was coronatreated, with the film thereafter being coated in the manner describedabove for Coated Film 1A. Several different Film No. 1 samples weretested, each having a different level of corona treatment. The filmswere corona treated using Enercon Treater (Model Number SS2542) coronatreatment machine, at power settings of 1.0, 1.75, 2.75 and 3.5 kW(kilowatts). Each of the films passed through the machine at a speed of100 feet per minute. The treated films were coated and tested for colortransfer as described in Film 1A, above. In all the cases except wherethe film was treated at a power of 1 kW, the color transfer wasexcellent. A slight ruboff of color during the meat filling process wasseen with the casing that was made from the film which was treated withcorona treater power of 1 kW. The rub-off for the film treated at 1 kWwas considered to be somewhat undesirable, as the rub-off produced anvisibly detectable uneven distribution of the color on the food product.However, no observable rub-off occurred for the films treated at thepower settings above 1.0 kW. This result was surprising andunpredictable.

EXAMPLE 5 Preventing Film Blocking through Use of Low-Tar Liquid SmokeFormulation

It was discovered that the selection of a liquid smoke having a low tarcontent reduced the tendency of the coated film to block, i.e., forsuccessive film wraps on a roll of film to adhere to one another. FilmNo. 1 was coated with a coating formulation in accordance with CoatingFormulation No. 1 as set forth in Example 1 above, except that insteadof the formulation containing Charsol Select® 24 liquid smoke, a low tarliquid smoke was selected, i.e., Special A liquid smoke, obtained fromRed Arrow Products Co. Inc., of Manitowoc, Wis. The resulting coatedfilms were evaluated for blocking by a method similar to ASTM3354—Procedure B (hereby incorporated in its entirety, by referencethereto), where a Kayeness™ blocking instrument was used. Samples werecut and layered and placed under a slab weighing 32 lbs. forapproximately 100 hours before testing. The testing was done in themachine direction. Maximum load was 212.8 grams. The sample with CharsolSelect® 24 liquid smoke did not separate at full load, i.e., 212.8grams, whereas the sample with low-tar smoke that was coated under thesame condition, separated at a load of 119 grams. This result wassurprising and unpredictable. Thus, preferably the liquid smoke has atar level of from 0 to 2%; more preferably from 0 to 1%; still morepreferably, from 0 to 0.5%.

EXAMPLE 6 Coating Formulation Containing Both Hydroxypropyl Starch andFibrinogen Resulted in Decreased Blocking

It was discovered that a coating formulation containing fibrinogen alsoreduced the tendancy of the coated film to block. The fibrinogen was thefibrinogen component of FIBERMIX® isolated components of blood fromcattle, which was obtained from FNA Foods, of Calgary, Alberta, Canada.Film No. 1 was coated with a coating formulation similar to CoatingFormulation No. 1, except that one-half of the PURE COTE™ hydroxypropylstarch was replaced with fibrinogen. Otherwise, the coating was carriedout as described above for coated film 1A. The coated film was testedfor blocking using the procedure described above. The sample separatedat 13 grams weight, i.e., a degree of blocking which is substantiallylower than that the weight applied to either of the films testedimmediately above. This result was surprising and unpredictable.

EXAMPLE 7 Reduction of Purge Loss via Modification of Cooking Procedure

This example demonstrates that the purge loss which occurs (using acasing coated with a color transfer agent {liquid smoke and caramel} andPURE COTE™ hydroxypropyl starch i.e., in accordance with the presentinvention) can be reduced by the modification of the conventionalcooking procedure. The conventional cooking procedure generally used inthe industry to cook turkey meat batter in a tubing or casing is agradient process, beginning at about 145° F. and ending at a final cooktemperature at about 170° F., over a period of from about 2 to 10 hours.Using a coated film as in Example 1, it was discovered that the purgeloss could be reduced by using an initial cooking of the turkey meatbatter at 190° F. for 12 minutes, followed by cooking employing theconventional cooking procedure described above. In Table I, immediatelybelow, results from the effect of this “spike-cooking” procedure areshown. In Table 3 is shown the loss due to purge seen in the firsttwelve minutes of the cooking done at 190° F. at 2 minute intervals upto 12 minutes. As can be seen from the results in Table 3, the purgeloss was reduced from 1.39% to 0.13% by precooking the meat at 190° F.for 12 minutes. Lesser amounts of purge loss reduction were obtained byprecooking the turkey meat batter for a lesser time period.

TABLE 3 (Effect of pre-heating at 190° F. on purge loss from a colortransfer casing) Treatment Time @ 190° F. Purge Loss (%) Depth of Cook(mm) Without Coating 0 min. 0.13 0 With coating 0 min 1.39 0 2 min 0.362 4 min 0.36 4 6 min 0.48 5 8 min 0.25 6 10 min 0.22 7 12 min 0.13 8

EXAMPLE 8 Purge Loss is Dependent on the Nature of the Uncooked Meat

It was also discovered that purge loss was also dependent on the natureof uncooked meat. For example, the turkey meat batter used in thecooking spike example above (Example 7) was instead made of chunks ofturkey meat. However, a similar color-transfer process was carried outbut instead of chunks of turkey meat, uncooked turkey meat batter wasused. The turkey meat batter had more surface area available for theextraction of the myofibrillar protein, resulting in greaterwater-binding capacity. The coating formulation was similar to theformulation used in the spike-cooking example above, and the cook cycleinvolved a cooking spike at 190° F. for 10 minutes. However, the purgeloss ranged from 0.02–0.04%, instead of 0.22% that was seen with theturkey meat batter used in the spike-cooking of Example 7 above. Thus,it was discovered that the amount of purge is inversely proportional tothe surface area of a meat product.

EXAMPLE 9 Presence of Fibrinogen in Coating Composition Reduced Purge

The presence of fibrinogen in the coating formulation was discovered toreduce the amount of purge, without having to use a spike heatingprocedure as described above. A fibrinogen-containing coatingformulation was made by the procedure described above, and thereafterused to coat Film No. 1. That is, Film No. 1 was coated with a coatingformulation similar to Coating Formulation No. 1, except that one-halfof the PURE COTE™ hydroxypropyl starch was replaced with fibrinogen.Otherwise, the coating was carried out as described above for coatedfilm 1A. The resulting coated film was used to package a turkey meatbatter product which was cooked and evaluated for purge. Even though noheating spike was used, the purge loss was found to be only 0.16%. Thisresult was surprising and unpredictable. See Table 1, which indicatesthat without fibrinogen, the purge loss was about 1.39%. Moreover, thismay indicate that the mechanism of the reduction in the extent of purgeloss by preheating is related to the mechanism resulting in thereduction in purge from the addition of fibrinogen to the coatingformulation may be very similar. That is, it could be that both the heatspike cooking procedure by itself, or the presence of fibrinogen in thecoating media, provide an interaction between the fibrinogen and themyofibril proteins that result in a protein skin on the surface of themeat product. The skin is probably formed in the early part of the cookcycle, retarding the migration of water from the meat blend.

EXAMPLE 10

It has also been discovered that by first coating a thermoplastic filmwith a first coating comprising binder, crosslinker, and additive, andthereafter coating this first coating with a second coating of, forexample soy protein isolate, the level of purge is reduced. This is animportant feature because typically for ham products the purge levelduring the existing smoking process in the industry ranges from about 10to 12 percent. By using the second coating over the first coating, i.e.,an “overcoat,” the level of purge for ham can be reduced from, e.g.,about to 10 to 12% purge loss, to, about 2% purge loss. Note that, as inExample 9, purge can be reduced without the presence of an overcoat, byproviding a blend of binders, e.g., a 50:50 blend of PURE COTE™hydroxypropyl starch and soy protein isolate.

Table 4, immediately below, shows the purge-lowering effect of providingthe first film layer, which comprises the binder, additive, andcrosslinking agent, with an overcoat layer which comprises either 100percent soy protein isolate, or a 50:50 blend of PURE COTE™hydroxypropyl starch and soy protein isolate. The film was used for thepackaging and cooking of a ham meat batter. As can be seen, for example,in Sample 1 and Sample 2, the level of purge goes down from 8.7% to 1.0%on overcoating with soy protein isolate. Similarly, as seen in Sample 3and Sample 4, the extent of purge goes down from 6.6% to 2.8% onovercoating with a 50:50 blend of soy protein isolate and PURE COTE™hydroxypropyl starch.

TABLE 4 Results of Sectioned and Formed Ham Test Purge Sample CoatingFormulation/ Loss Designation Overcoat Formulation (% by wt) 1 CoatingFormulation: 8.7 Binder: Pure-COTE (25% solids) Smoke: Charsol LFBSpecial A liquid smoke Color: Williamson 252 caramel Overcoat: None 2Coating Formulation: 1.0 Same as Sample 1 Overcoat Formulation: 35:10(wt:wt) soy protein isolate plus PURE COTE ™ aqueous blend 3 CoatingFormulation 6.6 Binder: PURE COTE ™ (25% solids) Smoke: Charsol LFBSpecial A liquid smoke Color: Warner Jenkins caramel Overcoat: None 4Coating Formulation: 2.8 Binder: 35:10 (wt:wt) soy protein isolate plusPURE COTE ™ aqueous blend Smoke: Charsol LFB Special A liquid smokeColor: Warner Jenkins caramel Overcoat: None

The Standard Mottling Test

The above-described procedure in Example 1 was carried out. A turkeymeat batter was then cooked for several hours in a high humidityenvironment at 180° F. After chilling, the cooked chubs were evaluatedfor color transfer. Samples were measured with the Gray Scale beforebeing stripped and evaluated for color uniformity.

The cooked turkey meat batter chubs were photographed using a color CCD(charge coupled device) video camera. The camera was mounted in a box 50cm above the bottom of the cabinet which also held a tub containing theimmersed chub being photographed. A bank of double 15 W fluorescentlamps was mounted on each side of the interior of the cabinet such thatthe light was striking the subject at approximately a 45 degree angle.The turkey meat batter chubs were immersed in a tub of water forphotographing to reduce the glare from the light sources. Images werecaptured using a video capture board and image analysis (IA) software(IP Lab Spectrum P, Signal Analytics Corporation, Vienna, Va.).

For purposes of image processing and data analysis, the colored picturesthat were captured were converted to grayscale images using the IAsoftware. A rectangular region of interest (ROI) encompassing themaximum amount of the product possible was selected (approximatelyone-third of the surface area of one side of the chub, which had acircumference of from about 8.5 to 9 inches, and length of about 10–11inches), and was analyzed for mean and standard deviations in pixelvalues using the analytical features of the software. The mean wassimply the average “grayness” of the image, and was not of particularinterest. The standard deviation was of great importance because it wasan indicator of the uniformity of the “grayness” in the image, and thusof the degree of color variation (i.e., mottling) on the surface of thechub.

The apparatus used in determining the grayness of the image was asfollows: Lights: Phillips Softone™ F15T8/SF, obtained from PhillipsLighting Co., of Somerset, N.J.; Housing for bulbs: Model XX-15L, UVPInc., San Gabriel, Calif. Camera: COHU Model 2222-1040/AL07, obtainedfrom COHU, Inc, San Diego, Calif. (the camera settings were F=1.25 andC=12); Video Capture Board: SCION CG-7, obtained from Scion Corporation,Frederick, Md.; Computer: Power Computing, Power Base 180 (now owned byApple Computer, Inc., Cupertino, Calif. (and uses Mac Operating System7.5.5); Imaging Software: IPLab Spectrum P, Signal Analytics Corp.,Vienna, Va.

FIG. 7 provides a schematic illustration of the setup for carrying outthe imaging of the chubs. In FIG. 7, lights 98 illuminates the uppersurface chub 100 (containing a cooked meat product) which was immersedin water 102 which, in turn, was held in open tub 104. Camera 106 wasused to record an image of the chub, which data was used to calculatethe standard deviation indicative of the degree of mottling on thesurface of chub 100. Lights 98 were positioned about 19 inches from oneanother. Camera 106 was positioned about 14 inches from the uppersurface of chub 100. Lights 98 were positioned about 10 inches from thesurface of chub 100.

Several different coating formultations similar to Coating FormulationNo. 1 (set forth above) were prepared and tested using the setupschematically illustrated in FIG. 7, as described above. However, thelevel of liquid smoke in the formulation was varied by factors of 0×,0.25×, 0.5×, 1.0×, and 2.0×, with the amount of all other components inthe coating formulation being kept constant, i.e., the same as inCoating Formulation No. 1, set forth above. The coated film was used forpackaging a chub in accordance with the Standard Mottling Test, setforth above, with the results being set forth in Table 5, below. In eachchub, three different areas were evaluated for mottling, totaling about95% of the total surface area of the chub, with each of the threeresults being averaged in the column on the far right.

TABLE 5 Sample Liquid Smoke Pixel Area Mean Pixel Std. Avg. Std. No.Factor (sq. pixels) Value Dev. Dev. 1-1 0 90531 92.85 23.52 1-2 0 9600092.78 25.36 23.3 1-3 0 83825 96.98 21.0 2-1 0.25 94842 96.57 18.11 2-20.25 91298 96.65 18.22 17.59 2-3 0.25 89094 105.02 16.44 3-1 0.5 9675898.94 18.09 3-2 0.5 97034 98.19 19.1 18.55 3-3 0.5 91776 104.7 18.45 4-11 87200 94.72 12.86 4-2 1 92904 99.98 12.14 12.56 4-3 1 79514 96.0112.67 5-1 2 95800 94.58 13.85 5-2 2 86400 101.67 15.72 13.44 5-3 2 9340590.67 10.76

As can be seen by correlating the above average standard deviationnumbers a well as the photographic images presented in FIGS. 7, 8, and9, average standard deviation is higher for more mottling, and lower forless mottling. Surprisingly, the combination of binder, caramel andliquid smoke resulted in decreased mottling as the amount of liquidsmoke increased up to a liquid smoke factor of 1. Average standarddeviation appears to level out for a liquid smoke factor of about 1.0and higher, which is the region of greatest effect of the liquid smokeas a crosslinker which reduces mottling.

FIGS. 8, 9, and 10 are photographs illustrating three different chubs,each having a different degree of mottling than the other. In additionto the above quantitative test which expresses color variation in termsof standard deviation of various pixel values obtained for the chub,qualitative evaluation has also been performed. On a scale of 1 to 3,with 3 representing an undesirably high degree of mottling and 1representing a low degree of mottling or no visible mottling, the chubillustrated in FIG. 8 exhibited a level of mottling of 3. The chub ofFIG. 9 exhibited a level of mottling of 2.5, and the chub of FIG. 10illustrated a degree of mottling of 1. The film according to the presentinvention, when subjected to a Standard Mottling Test as describedabove, exhibits a degree of mottling of from about 1 to about 2.5, morepreferably from about 1 to 2.

Without being limited by the theory set forth below, a highly preferredembodiment of the present invention is believed to operate as follows. Athermoplastic film is coated with an aqueous coating compositioncomprising: (a) a binder which is a hydrocolloid (e.g., apolysaccharide) or a protein, together with (b) an additive, (c) aplasticizer, (d) a crosslinking agent, and (e) water. The liquidcomposition is coated onto the thermoplastic film, and adheres to thefilm upon drying, due to the polar interaction between the film and thebinder. Moreover, the dried composition is rendered more flexible due topresence of the plasticizer. The dried composition, in the form of acoating, is cohesive because of the nature of the binder and thecrosslinking agent. Upon exposing the coating to a flowing high moisturemeat product, the coating remains adhered to the thermoplastic filmbecause of the high level of adhesion of the coating to the film. Whilerapid hydration alone would cause a loss of adhesion of the coating tothe film, the nature of the binder, together with the crosslinkingagent, is believed to control the rate of hydration of the coating. Thiscontrolled rate of hydration permits, for example, the filling of acasing to form a chub, and the interim storage of the uncooked chub,without the coating components becoming unbound from the film prior tothe initiation of cooking. However, upon initiating cooking, the coatingforms a hydrated gel which thereafter transfers to the meat product. Thetransfer includes the binder, the additive, and the crosslinking agent,which adhere to the meat product via various bonds formed between thebinder and the meat protein, especially the myofibrillar protein. Thebond between the binder and the myofibrillar protein results in theformation of a skin, which reduces the tendency for the meat to formpurge.

Although the present invention has been described with reference toparticular means, materials, and embodiments, it should be noted thatthe invention is not to be limited to the particulars disclosed, andextends to all equivalents of the expressly claimed subject matter.

1. A multilayer additive-transfer film suitable for cook-in processingof food products, comprising: (A) a first layer, comprising (i) a bindercomprising at least one member selected from the group consisting ofpolysaccharide and protein, and (ii) a crosslinking agent comprising acompound with at least two carbonyl groups; (B) a second layer,comprising a non-water-soluble thermoplastic polymer comprising at leastone member selected from polyolefin, polyamide, polyester,polyvinylidene chloride, polyvinyl chloride, and polystyrene; and (C) athird layer, comprising (i) a binder comprising at least one memberselected from the group consisting of polysaccharide and protein, and(ii) an additive comprising at least one member selected from the groupconsisting of flavor, fragrance, colorant, antimicrobial agent,antioxidant, chelating agent, and odor absorbent, said additive beingbound to said binder with at least one member selected from a covalentbond, an ionic bond, a hydrogen bond, and a dipole-dipole interaction;wherein, the first layer is positioned between the second and thirdlayers; and during cooking of a food product surrounded by saidmultilayer additive-transfer film, at least a portion of said binder andsaid additive in said third layer are transferred from said third layerto the food product.
 2. The multilayer film of claim 1, furtherincluding a crosslinking agent in the third layer.
 3. The multilayerfilm of claim 1, further including an additive in the first layer. 4.The multilayer film of claim 1, wherein the binder in the first layercomprises at least one member selected from alginate, methyl cellulose,hydroxypropyl starch, hydroxypropylmethyl starch, hydroxymethylcellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose,carboxymethyl cellulose, cellulose esterified with 1-octenyl succinicanhydride, chitin, chitosan, gliadin, glutenin, globulin, albumin,prolamin, thrombin, pectin, carrageenan, konjac flour-glucomannin,fibrinogen, casein, soy protein, whey protein, and wheat protein.
 5. Themultilayer film of claim 4, wherein the binder in the first layercomprises at least one member selected from alginate, methyl cellulose,hydroxypropyl starch, hydroxypropylmethyl starch, hydroxymethylcellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose,carboxymethyl cellulose, chitosan, globulin, albumin, thrombin, pectin,carrageenan, konjac flour-glucomannin, fibrinogen, casein, soy protein,and whey protein.
 6. The multilayer film of claim 1, wherein the binderin the third layer comprises at least one member selected from alginate,methyl cellulose, hydroxypropyl starch, hydroxypropylniethyl starch,hydroxymethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethylcellulose, carboxymethyl cellulose, cellulose esterified with 1-octenylsuccinic anhydride, chitin, chitosan, gliadin, glutenin, globulin,albumin, prolamin, thrombin, pectin, carrageenan, konjacflour-glucomannin, fibrinogen, casein, soy protein, whey protein, andwheat protein.
 7. The multilayer film of claim 6, wherein the binder inthe third layer comprises at least one member selected from celluloseesterified with 1-octenyl succinic anhydride, chitin, gliadin, glutenin,prolamin, and wheat protein.
 8. The multilayer film of claim 1, whereinthe crosslinking agent comprises at least one member selected frommalose, glutaraldehyde, glyoxal, dicarboxylic acid, ester ofdicarboxylic acid, urea formaldehyde, melamine formaldehyde,trimethylol-melamine, organic compound containing at least 2 sulfhydrylgroups, and a component in liquid smoke comprising at least two carbonylgroups.
 9. The multilayer film of claim 1, wherein the first layer isdirectly adhered to the second layer.
 10. The multilayer film of claim1, wherein the third layer is directly adhered to the first layer. 11.The multilayer film of claim 1, wherein the binder in the first layercomprises (A) a first binder comprising at least one member selectedfrom alginate, methyl cellulose, hydroxypropyl starch,hydroxypropylmethyl starch, hydroxymethyl cellulose, hydroxypropylcellulose, hydroxypropylmethyl cellulose, carboxymethyl cellulose,cellulose esterified with 1-octenyl succinic anhydride, chitin, andchitosan; and (B) a second binder comprising at least one memberselected from gliadin, glutenin, globulin, albumin, prolarnin, thrombin,pectin, carrageenan, konjac flour-glucomannin, fibrinogen, casein, soyprotein, whey protein, and wheat protein.
 12. The multilayer film ofclaim 11, further including a crosslinking agent in the third layer. 13.The multilayer film of claim 11, further including an additive in thefirst layer.
 14. A multilayer additive-transfer film suitable forcook-in processing of food products, comprising: (A) a first layer,comprising (i) a binder composition, comprising (a) a first bindercomprising at least one member selected from alginate, methyl cellulose,hydroxypropyl starch, hydroxypropylmethyl starch, hydroxymethylcellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose,carboxymethyl cellulose, cellulose esterified with 1-octenyl succinicanhydride, chitin, and chitosan, and (b) a second binder comprising atleast one member selected from gliadin, glutenin, globulin, albumin,prolamin, thrombin, pectin, carrageenan, konjac flour-glucomannin,fibrinogen, casein, soy protein, whey protein, and wheat protein, (ii)an additive comprising at least one member selected from the groupconsisting of flavor, fragrance, colorant, antimicrobial agent,antioxidant, chelating agent, and odor absorbent, said additive beingbound to said binder composition with at least one member selected froma covalent bond, an ionic bond, a hydrogen bond, and a dipole—dipoleinteraction, and (iii) a crosslinking agent comprising a compound withat least two carbonyl groups; and (B) a second layer, comprising anon-water-soluble thermoplastic polymer comprising at least one memberselected from polyolefin, polyamide, polyester, polyvinylidene chloride,polyvinyl chloride, and polystyrene, (C) a third layer wherein, thefirst layer is positioned between the second and third layers, andduring cooking of a food product surrounded by said multilayeradditive-transfer film, at least a portion of said binder compositionand said additive in said first layer are transferred from said firstlayer to the food product.
 15. The multilayer film of claim 14, whereinthe third layer comprises at least one member selected from the groupconsisting of polysaccharide and protein.
 16. The multilayer film ofclaim 15, further including a crosslinking agent in the third layer. 17.The multilayer film of claim 15, further including an additive in thethird layer.
 18. The multilayer film of claim 15, wherein the thirdlayer comprises at least one member selected from alginate, methylcellulose, hydroxypropyl starch, hydroxypropylmethyl starch,hydroxymethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethylcellulose, carboxymethyl cellulose, cellulose esterified with 1-octenylsuccinic anhydride, chitin, chitosan, gliadin, glutenin, globulin,albumin, prolamin, thrombin, pectin, carrageenan, konjacflour-glucomannin, fibrinogen, casein, soy protein, whey protein, andwheat protein.